In response to the use of chemical weapons on Idlib Province in Syria, President Trump ordered 59 Tomahawk cruise missile strikes on Syrian military targets. Following a fact pattern, I will conclude that while the April 6, 2017 U.S. strike on Syria’s Al Shayrat air force base was not strictly legal under international law, it meets many principles of jus ad bellum and jus in bello. Further emerging international norms of responsibility regarding the force of way may exempt the U.S. from international legal condemnation.
The American public and the international community were surprised by the decisiveness with which the Trump administration responded to the Assad-ordered April 4, 2017 chemical weapons attack on Idlib Province in Syria, when they ordered 59 Tomahawk cruise missile strikes on key Syrian military targets just two days later. As details of the missile strike emerged, political pundits took to the airwaves to debate the legality of the President’s order. Clarification of the issues surrounding this debate is the subject of this essay. Was the April 6, 2017, U.S. strike on Syria’s Al Shayrat air force base, in response to the purported use of chemical weapons by the Syrian regime, legal under the laws of war? Is the Trump administration’s argument for the legality of the strike justified under international and domestic law? In considering the legality of the missile strike, the fact pattern will be considered in the context of both jus ad bellum and jus in bello legal frameworks. Following this analysis, the conclusion will be drawn that while the April 6, 2017 US strike on Syria’s Al Shayrat air force base may not be considered strictly legal under the laws of war, it may still be justified under emerging international norms regarding the use of force.
THE FACT PATTERN
First, it is necessary to establish the fact pattern of the April 6 missile strike. During his trip to the Mar-a-Lago estate in Florida, where he hosted a dinner for Chinese President Xi Jinping, President Donald J. Trump convened a “decision meeting” with many of his national security advisors to deliberate on potential measures of military action against Assad’s forces in Syria. Defense Secretary James Mattis presented a range of options to the President, who then consulted with Cabinet members and other top advisors including his son-in-law Jared Kushner, National Security Advisor Lieutenant General H. R. McMaster, and the White House Chief Strategist Stephen Bannon. Trump decided to pursue an attack “at the more limited end of the options” offered by Secretary Mattis, authorizing the launch of 59 Tomahawk cruise missiles from the USS Porter and the USS Ross shortly before dinner with President Xi. Shortly after the missiles were launched at approximately 8:40 pm Eastern time (4:40 am in Syria), Trump appeared outside to announce the strike and to deliver the following remarks:
Tonight, I ordered a targeted military strike on the airfield in Syria from where the chemical attack was launched… It is in this vital national security of the United States to prevent and deter the spread and use of deadly chemical weapons…There can be no dispute that Syria used banned chemical weapons, violated its obligations under the Chemical Weapons Convention and ignored the urging of the UN Security Council. Years of previous attempts at changing Assad’s behavior have all failed and failed very dramatically.
Official government statements and reporting on the aftermath of the missile strike offered contradicting assessments of the strike’s effectiveness. A press release from the Department of Defense and Secretary Mattis claimed that 58 of 59 of the Tomahawk cruise missiles had reached their intended targets across the base, resulting in “the damage or destruction of fuel and ammunition sites, air defense capabilities, and 20 percent of Syria’s operational aircraft.” The statement further explained that “the Syrian government has lost the ability to refuel or rearm aircraft at Shayrat airfield and at this point, use of the runway is of idle military interest.” Russia’s Defense Ministry spokesman, Major-General Igor Konashenkov, refuted the United States’ claims of success, stating that only 23 of the 59 Tomahawk cruise missiles reached their targets and only six Mikoyan MiG-23 fighter jets were destroyed. Russian government reports should be received with a fair dose of skepticism, but other sources of evidence indicated the strike resulted in limited operational destruction. Indeed, regime and oppositional forces reported that military flights resumed the weekend after the strike. Yet the efficacy of the strike does not seem to have factored into Trump’s calculus. His statements emphasize the importance of deterring the future use of chemical weapons by way of flexing military might and costly signaling, rather than completely inhibiting the Assad regime’s military capability.
The missile strike cannot be analyzed in a vacuum, as both the lead-up and aftermath of the event are important for proper contextualization. The specifics of the chemical weapons attack to which Trump was responding are of particular significance. On April 4, 2017, a chemical agent was reportedly dropped on the rebel-held town of Khan Sheikhoun in Idlib Province. Numerous international organizations reported that over 100 people were killed in the attack and more than 500 were injured—at least 25% of the casualties being children. While many victims were able to be treated locally, a significant number of them required transportation across the Turkish border to receive proper medical treatment. From the symptoms displayed by those Syrians transported, the Turkish government, the World Health Organization, and the Organization for the Prohibition of Chemical Weapons identified the chemical weapon as the banned nerve agent Sarin. Additionally, the Pentagon worked to determine the actor responsible for the attack, eventually releasing a flight path pinpointing the Assad regime’s Shayrat air base as the origin for the planes carrying the weapon.
In response to the illegal use of Sarin, the international community and Trump administration officials condemned the attack. As a signatory to the Chemical Weapons Convention (CWC) and per a 2014 agreement between Russia and the United States, the Syrian regime was supposed to have declared all of its chemical weapon stockpiles, completely disarm and dispose of its chemical weaponry by 2014, and never again use chemical weapons—as purported to have done by crossing President Obama’s “red line” in 2013. Not only did the April attack violate Syria’s commitment to the international community as a signatory to the CWC, it also flew in the face of American goodwill while illustrating the potential errors made by the Obama administrations’ regarding efforts to destroy Syria’s chemical weapon capabilities through diplomacy, and not military force.
Finding the culprit and targeting them through legal means has been a challenging task, one not helped by the Syrian regime and ally Russia refusing to accept responsibility for the attack. Consequently, France, the UK, the United States, and many other nations began efforts within the UN Security Council and broader international system to place culpability on the Syrian regime. Speaking at the emergency UN Security Council Meeting on Chemical Weapons in Syria one day later, U.S. Ambassador to the UN Nikki Haley remarked:
We know that yesterday’s attack bears all the hallmarks of the Assad regime’s use of chemical weapons. We know that Assad has used these weapons against the Syrian people before. That was confirmed by this Council’s own independent team of investigators. We know that yesterday’s attack was a new low, even for the barbaric Assad regime…
Ambassador Haley also foreshadowed the possibility of a forceful American response, when she remarked “that in the life of the United Nations, there are times when we are compelled to take collective action…When the United Nations Consistently Fails in its duty to act collectively, there are times in the life of states that we are compelled to take our own action.”
Defense Secretary Mattis offered a blunt condemnation, relaying that the chemical weapons use “was a heinous act and will be treated as such.” His counterpart in the State Department, Secretary Rex Tillerson, diplomatically added that “anyone who uses chemical weapons to attack his own people shows a fundamental disregard for human decency and must be held accountable.” None of these officials nor the President explicitly committed to taking unilateral action against the Syrian regime following its use of chemical weapons, but the US missile strike two days later should have come as no surprise given their remarks on the subject.
The aftermath of the US missile strike is also important to consider. Both allies and foreign adversaries of the United States were quick to weigh in with their support or disapproval of the strike. The vast majority of the international community did not hesitate to back the United States’ unilateral action, as powerful global actors such as France, the UK, Germany, Japan, the European Union and NATO joined regional actors Turkey, Jordan, Saudi Arabia and Israel in expressing their approval in one way or another. The usual suspects, Russia, Iran, China, and North Korea, declined to support the strike. Russian President Vladimir Putin said the strike was “an aggression against a sovereign state in violation of the norms of international law.” The Chinese response, perhaps due in part to the optics of President Xi dining with President Trump as the strike was carried out, was more muted in its opposition: “China always opposes the use of force in international affairs and we advocate resolving disputes peacefully through dialogues. … We always hold that the Syrian issue should be resolved through political means.”
The international tension created by the unilateral action materialized in the flurry of activity at the United Nations Security Council following the strike. A current member of the Council, Bolivia called for an emergency closed session to discuss what they believed was “an extremely, extremely serious violation of international law.” As that month’s chair of the Council, US Ambassador Haley retorted that whatever Bolivia wanted to discuss, it must do so in a public session so that “any country that chooses to defend the atrocities of the Syrian regime will have to do so in full public view, for all the world to hear.” Simultaneously, France, the United Kingdom, and the United States worked to produce a UN resolution condemning the chemical weapon use in Syria and emphasizing Syria’s obligations under the Chemical Weapons Convention. The resolution would later fail, as expected, by way of Russia’s veto power.
Since then, the international community, news organizations, and legal scholars have debated the legality of the missile strike outside the confines of the official United Nations system. With the fact pattern of the missile strike and its general context established, it is now appropriate to conduct this legal analysis and to determine if the Trump administration’s own justification for the strike passes muster under domestic and international law. The scope of this legal analysis will begin large and narrow progressively. Considerations of jus ad bellum (just war and use of force) will precede considerations of jus in bello (international humanitarian law).
CONSIDERATIONS OF JUS AD BELLUM: JUST WAR AND THE USE OF FORCE
Was the US Tomahawk cruise missile strike, originating from two USS ships in the East Mediterranean Sea, legal under the laws of war relevant to considerations of jus ad bellum?
For legal clarification, the principles of jus ad bellum are commonly defined as: the principle of proper authority, the principle of reasonable probability of success, the principle of proportionality, the principle of last resort, and the principle of just cause. The principle of proper authority stipulates that “a war is just only if waged by a legitimate authority,” the principle of reasonable probability of success requires that “there must be good grounds…that the desired outcome can be achieved,” and the principle of proportionality demands that “the violence used in the war must be proportional to the attack suffered.” Additionally, the principle of last resort requires “that all non-violent options must be exhausted” prior to the use of just force while the principle of just cause is satisfied only if “the aim of war” is not “to pursue narrowly defined national interests, but rather to re-establish a just peace.” These five principles will be tackled, roughly, in increasing order of complexity and significance as applied to this case.
The principle of right and proper authority is generally not controversial in this case, as it is beyond argument that the United States is itself a sovereign nation that derives legitimate governing authority from its own population. Its membership and leadership within the United Nations and a multitude of international organizations demonstrate its sovereignty. A further requisite of this principle is that a nation operating under jus ad bellum must assume public responsibility for its actions. The fact pattern demonstrates the United States’ willingness to take responsibility for the strike. In fact, the United States was painstakingly transparent in handling the entire strike, releasing specific details, media press releases, and even a video of the Tomahawk cruise missiles being fired from one of the destroyers. The United States also notified the international community and the UN Security Council of the strike through remarks made by Ambassador Haley on April 7, 2017: “Our military destroyed the airfield from which this week’s chemical strike took place. We were fully justified in doing so.” The United States acted as a sovereign nation, with proper authority and for the whole world to see.
What is more interesting to consider tangentially to this principle, however, is that, as a sovereign nation, how does the United States itself regulate and justify such military action? In other words, what domestic considerations must be met for the United States itself to act in accordance to the proper authority principle of jus ad bellum?
The President’s domestic authority to act on behalf of the United States is well-established. The President’s authority to conduct the nation’s foreign affairs and serve as its Commander in Chief are derived from Article 2 of the U.S. Constitution. The President’s authority is not unlimited considering the 1973 War Powers Resolution places conditions on unilateral action by the President regarding military decisions. The President may only enter an armed conflict after a declaration of war by Congress, another form of statutory authorization is granted, or during a state of emergency resulting from an attack on the nation or its forces. Furthermore, the President must by way of public notification to Congress disclose military action within 48 hours of the action taking place, and no form of military action may continue after 60 days without Congress’ authorization. Trump followed through with this requirement for public notification on April 8, 2017, writing to the Speaker of the House and President Pro Tempore of the Senate. In addition to detailing the missile strike, Trump adds that he “acted in the vital national security and foreign policy interests of the United States, pursuant to [his] constitutional authority to conduct foreign relations and as Commander in Chief and Chief Executive.” He also noted that the intent of the notification was not only to work with Congress but to remain in compliance with the War Powers Resolution itself.
President Trump met his minimum domestic legal requirements under Article 2 and the War Powers Act. Although some critics, like Senator Rand Paul (R-KY) faulted the President for not consulting with Congress prior to the strike, the War Powers Resolution reads that the President must consult Congress prior to military action only “in every possible instance.” It can be argued by the administration this was not feasible in this situation because the element of surprise was an absolute necessity. Thus, Trump’s consultation with Congress after-the-fact satisfies his legal obligation.
Although not technically necessary, Trump could have further strengthened his argument for domestic legal authority by referring to the 2002 authorization for military force in Iraq, or House Joint Resolution 114. Specifically, Trump could argue the missile strike was pursuant to H.J. Res. 114’s clause that the action “is consistent with the United States and other countries continuing to take necessary actions against international terrorists and terrorist organizations” and that the strike in Syria “defend[s] U.S. national security against the continuing threat posed by Iraq.” That said, this argument requires jumping through too many mental hoops to link the Syrian chemical attack to terrorists in Iraq, so it is ultimately beneficial that the Trump administration did not pursue this line of reasoning when seeking domestic legal cover.
The principle of a reasonable probability of success is assumed in this case, given the relative expertise of the Pentagon in crafting their measures of force. In light of this principle, one should consider the unintended consequences of the strike. While the missile strike itself may have had a reasonable probability of success in hitting its targets, will the short-term achievements of the strike outweigh the long term negative effects, if any? A few hypothetical events follow. In the aftermath of the strike, Russia suspended air cooperation with the United States in Syria. This agreement of cooperation was meant to avert unintended miscommunication between the two nations as they conduct separate military exercises in the Syrian civil war. The risk of escalation between them has therefore increased as a result of the missile strike. Another plausible long-term fallout from the missile strike is diminished US capacity to combat ISIS terrorists due to decreased levels of Russian or international support. Despite its significant improbability, another risky gamble in ordering the strike was giving Syria an excuse to declare war on the United States. If any of these scenarios had come to pass or do come to pass in the future, and more harm than good results from the US strike, then under the UN Charter the strike is unjustified. Evidence so far has not demonstrated the possibility of any of these scenarios and since the debate over just how bad an “unintended consequence” may be is up to interpretation, we will assume that (barring an unforeseen occurrence) the strike is justified under the principle of a reasonable probability of success.
The principle of last resort appears to be satisfied in this case as well, at least in the eyes of the United States and its allies — although foreign adversaries may argue the opposite. In the aforementioned remarks, Ambassador Haley explicitly noted that the United Nations and the international system have repeatedly failed to solve the Syrian issue despite numerous opportunities to do so. The failure of the UN Security Council to approve the resolution condemning the use of chemical weapons in Syria further demonstrates a lack of international political will in settling the issue. Assad’s blatant disregard for the US-Russia brokered agreement on eliminating Syria’s chemical weapons represents another exhausted political avenue. There have already been three negotiated ceasefires during the Syrian conflict, and yet zero tangible indications of long-term peace or resolution because of them. Some even argue these political ceasefires have simply become “another form of warfare.” Idealists may believe in the possibility of a political rather than a military solution, but the United Nation’s failure to act prior to and after the use of chemical weapons grants credibility to the United States’ argument that this use of force was in accordance with the principle of last resort.
The following principle of proportionality applies to both jus ad bellum and jus in bello, but within jus ad bellum refers specifically to the use of force itself as proportional to the violence sustained by the offense. In other terms, was the use of force on behalf of the United States a proportional response to the use of chemical weapons by Syria? Generally, this principle is not too controversial. Targeting the infrastructure of one airbase from which a chemical weapons strike — a crime against humanity — was carried out seems proportional. This assumed proportionality rests upon an analysis of how other states reacted to similar uses of chemical or biological weapons or crimes against humanity in the past — and the response from the international legal community. An analysis of NATO’s intervention in Kosovo applies here.
On March 24, 1999, NATO initiated a sustained air campaign against the Federal Republic of Yugoslavia in Kosovo, during the Kosovo War. The conflict was fought between the ethnic majority Serbians led by President Milosevic and the ethnic minority Kosovar Albanians, who had enjoyed relative freedom within Yugoslavia until Milosevic attempted to bring them under greater state control. With reports of mass killings of Kosovar Albanians and a large-scale refugee crisis, NATO members acted to suppress what they considered a genocide on the part of the Serbian majority — a crime against humanity. NATO’s sustained air campaign against this crime mirrors the United States’ use of force against Syria’s own crime against humanity, the use of chemical weapons. The relative proportionality involved in both situations appears comparable, and therefore if the NATO intervention in Kosovo fulfills the principle of proportionality, then the jus ad bellum principle of proportionality is satisfied for the US strike in Syria.
That the overall legality of the NATO intervention in Kosovo is still highly controversial points to the main legal sticking point within jus ad bellum regarding the US missile strike in Syria: the principle of just cause. Although both the NATO intervention in Kosovo and the US missile strike in Syria appear to satisfy the principle of proportionality, this is only possible if it is held true that both entities were acting with just cause in the first place. Under international law and Article 2(4) of the UN Charter, “All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.” In other words, the threat or use of force is normally illegal. The UN Charter is very specific regarding when the use of force has just cause and is legal: either when the UN Security Council authorizes the use of force or a state invokes Article 51, which provides for “the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations.” To fulfill the principle of just cause in ordering the missile strike, therefore, the United States would either have needed a UN Security Council resolution authorizing the strike or the US would need to have invoked self-defense or collective self-defense. As no such Security Council resolution was granted, then the US must rest on self-defense or collective self-defense if it’s air strike hopes to pass legal muster under explicit international law.
The US missile strike was clearly a violation of Article 2(4) as it infringed on the sovereignty of Syria. The evidence proves that Syria’s air base, infrastructure, military equipment, and personnel were attacked by the United States in a use of force. In addition, the lack of a UN Security Council resolution authorizing this use of force necessitated invoking Article 51 if the United States wished to have its violation of Article 2(4) legally justified. However, the legal justification for invoking Article 51 on the part of the US in response to the use of chemical weapons in Syria is difficult to grant. The use of chemical weapons did not occur on American territory nor did it result in any American casualties, and it does not seem to have been intended to achieve either. Invoking Article 51 in the wake of the 9/11 terrorist attacks was a clear-cut response to an attack on American soil; the Syrian chemical weapons attack happened against non-US forces thousands of miles away and represents a fundamentally different situation. As the immediate security of the United States does not appear to have been threatened by the chemical weapons attack, the United States did not have proper legal authority to invoke Article 51.
ILLEGAL BUT JUSTIFIED? EMERGING NORMS OF INTERNATIONAL LAW
Without authorization by the UN Security Council or ample grounds to invoke Article 51, the Trump administration did not have proper legal authority to conduct the air strike under explicit international law. However, there exists an emerging body of literature and scholarship on norms of international law that, while not explicitly codified in the laws of war, may allow the Trump administration to justify its actions. In a widely-distributed government memo, the administration argues that domestically, the President acted in accordance with Article 2 of the Constitution by defending U.S. vital interests abroad, “which the use of chemical weapons threatens.” We have already concluded Trump was justified domestically on this issue. Transitioning to an international perspective, the document argues that “the U.S. strikes were a justified use of force because of several factors, including promoting regional stability, discouraging the use of chemical weapons, and protecting a civilian population from humanitarian atrocities,” and the use of chemical weapons “presents a clear threat to regional stability and security as well as the national security interests of the United States [and] our allies.” Finally, the document concludes that “Assad’s actions have fueled the rise of terrorist groups such as the Islamic State and al-Qaeda, displaced millions of Syrians and destabilized the region… Weapons of mass destruction use by any actor lowers the threshold for others that may seek to follow suit and threatens the international legal regime prohibiting the use of chemical weapons.”
This document is extremely significant in analyzing the Trump administration’s attempt to secure international legal cover for the missile strike. The administration appears to point to three main justifications for its actions: the self-defense of the United States and the collective self-defense of its allies, enforcing international norms regarding chemical weapon use, and humanitarian intervention. The merits of each argument will be tackled in turn.
First, can the Trump administration use the self-defense of the United States and the collective self-defense of its allies as legal justification for just cause? As previously discussed, it would be difficult for the Trump administration to invoke its own self-defense under Article 51. While Trump argues that the proliferation of chemical weapons anywhere is dangerous to national self-defense, or that the presence of chemical weapons creates the possibility of terrorists gaining access to them, the argument is weak that the use of chemical weapons on Syrian civilians represents an imminent threat to the national security of the United States despite the enormity of the attack. It seems most assuredly that the self-defense clause of Article 51 does not apply in this case.
That said, while the United States couldn’t justify protecting its own self-defense under UN rules, Article 51 does provide for the collective self-defense of other UN member states. While the conflict in Syria and the use of chemical weapons may not pose an imminent threat to the United States, it surely presents a danger to surrounding nations such as Turkey. Many of the victims of the chemical attack were themselves transported to Turkey for medical assistance. Not only must allies of the United States, like Turkey, deal with the complex refugee crisis created as a result of the broader Syrian conflict, they must now face the uncertainty of chemical weapons in the hands of an unstable regime. Turkey and other regional allies applauded the use of force on behalf of the United States; in some manner, the US was simply acting as a proxy for the Turks and other allies in their right to defend their own self-defense in accordance with Article 51. While this collective self-defense argument still cannot legally cover the US air strike since no regional ally invoked Article 51, arguing for general justification of the strike in terms of collective self-defense is not without merit.
If not in the name of US self-defense, can the Trump administration then use the enforcement of international norms regarding chemical weapon use as legal justification for just cause? The outlawry of chemical weapons is a well-established international norm under the Chemical Weapons Convention, the Geneva Conventions, the Organization for the Prohibition of Chemical Weapons and many other forms of customary international law. The UN Security Council itself has repeatedly reaffirmed the illegality of the use of chemical weapons. UN Security Council Resolution 2118 (2013), in recalling previous resolutions 1540 (2004), 2042 (2012), and 2043 (2012), begins by determining “that the use of chemical weapons anywhere constitutes a threat to international peace and security” and “condemns in the strongest terms any use of chemical weapons in the Syrian Arab Republic.” Furthermore, the resolution “underscores that no party in Syria should use, develop, produce, acquire, stockpile, retain, or transfer chemical weapons” and “expresses its strong conviction that those individuals responsible for the use of chemical weapons in the Syrian Arab Republic should be held accountable.” It is clear from the text of this resolution that the UN Security Council has already condemned the use of chemical weapons in Syria, regardless of its failure to pass another resolution condemning the specific attack on April 4, 2017.
As a member of the United Nations and a permanent member on the Security Council, does the United States not then have an obligation to carry out the spirit of Resolution 2118 and other prior resolutions regarding the use of chemical weapons? One thorn in the side of this argument is the clause within the resolution that the UN reaffirms “its strong commitment to the sovereignty, independence and territorial integrity of the Syrian Arab Republic.” Infringing on Syria’s sovereignty, even in the spirit of the bulk of the resolution, therefore appears illegal.
That said, Lee Feinstein and Anne-Marie Slaughter argue the United States may be justified in doing so according to their formulation of “A Duty to Prevent,” in that states and the international community must be proactive, not reactive, in the face of WMD development and deployment. Their formulation of the theory is as follows:
First, it seeks to control not only the proliferation of WMD but also people who possess them. Second, it emphasizes prevention, calling on the international community to act early in order to be effective and develop a menu of potential measures aimed at particular governments especially measures that can be taken well short of any use of force. Third, the duty to prevent should be exercised collectively, through a global or regional organization.
This excerpt presents a challenge in justifying the US missile strike through their theory, however, as they specify that “the duty to prevent should be exercised collectively.” The United States clearly acted unilaterally in this case.
What if collective action is impossible, however, as the United States deemed due to the lack of action from the UN Security Council? Feinstein and Slaughter note the Bush doctrine of unilateral “preemptive action,” accepting that “the use of force to preempt an imminent threat has always been part of international law, and it has been an option that the United States has held in quiet reserve and occasionally used.” They qualify this sentiment, nevertheless, admitting that “the preemptive use of force is often difficult to justify because clear evidence that a threat is imminent is rare.” This is exactly why many critics contend the US strike is illegal: the use of chemical weapons in another country does not pose an imminent threat to the United States. Here the Trump administration ostensibly disagrees, claiming that allowing the norm against using chemical weapons to be degraded poses an existential threat to the United States and its allies. Ultimately, this argument for acting unilaterally to protect international law and norms requires that other international laws and norms be broken at the same time, and therefore is deemed unsatisfactory in providing legal cover for the US missile strike despite its plausible justification under the emerging norm of a “Duty to Prevent.”
More significantly, could the Trump administration use the necessity of humanitarian intervention as legal justification for just cause? Many previous uses of force, including the Kosovo intervention, have escaped international legal condemnation by adopting the same line of reasoning. This line of reasoning points to another emerging norm in international law, the so-called “Responsibility to Protect.” This emerging norm “holds that today UN member states have a responsibility to protect the lives, liberty, and basic human rights of their citizens, and that if they fail or are unable to carry it out, the international community has a responsibility to step in.” This theory was formulated in the aftermath of many of the humanitarian crises in the 1990’s, including the aforementioned Kosovo intervention. When President Obama sought an authorization for military force in the 2011 Libyan conflict, the authorization for military force granted to him used Kosovo as a precedent for humanitarian intervention. It states that “President Clinton justified extensive airstrikes” in Kosovo as the conflict had “no natural boundaries, pushing refugees across borders and potentially drawing in neighboring countries. The Kosovo region [was] a tinderbox that could ignite a wider European war with dangerous consequences to the United States.” Obama extended this concern of humanitarian disaster including “large refugee movements, destabilizing neighboring countries, and…wider conflict” to justify the use of force in Libya. The Trump administration would only be further applying this conception of a responsibility to protect against humanitarian disaster in the case of the Syrian air strike, allowing for the possibility of justification under emerging international norms. Although applying this theory to the Syrian airstrike necessitates stretching the legal analogy—since the Kosovo and Libyan intervention were collective through NATO and the UN, respectively, and the Syria strike was unilateral—general normative justification under this theory remains viable.
FUTHER CONSIDERATIONS: JUS IN BELLO — INTERNATIONAL HUMANITARIAN LAW
To supplement the jus ad bellum legal analysis of the missile strike, the attack may also be analyzed through the purview of jus in bello. Jus in bello, or international humanitarian law, is constituted by the two main principles of distinction and proportionality as described in the Geneva Conventions. From Articles 51 and 52 of Protocol I of the Geneva Conventions, the principle of distinction requires that no civilian or civilian objects are targeted in war. The United States’ air strike exclusively targeted a Syrian military air base and its infrastructure, the same base from which the chemical attack was initiated. The United States neither attacked civilians nor did it intend to target Syrian soldiers, thus going beyond the bare minimum required to satisfy the principle of distinction.
The principle of proportionality, similar to that under jus ad bellum, requires the force used in armed conflict to be proportional to the threat posed or violence committed. First, the decision to use Tomahawk cruise missiles aids in satisfying this principle. According to one expert, “Tomahawks have less explosive yield than larger bombs carried by manned U.S. aircraft” and there is even “a specific variant of the Tomahawk that can carry cluster munitions that separate over a target, causing fragmentation and incendiary damage that could destroy vehicles, supply depots and aircraft on a flight line.” The Tomahawk cruise missiles were chosen consistent with the objective of destroying the base’s infrastructure and aircraft, not for indiscriminate killings or disproportional damage. Not only did the United States use a less-powerful and more precise weapon, but the US also alerted Russian forces near the base of the impending strike to ensure they were not targeted. In terms of responding with force, therefore, the US air strike was carried out with sufficient caution and reserve that the principle of proportionality is satisfied. The two main principles of international humanitarian law thus appear satisfied through the fact pattern of the air strike.
However, the air strike would only be considered a legal use of force if it passed both jus in bello and jus ad bellum requirements under international law. Although this jus in bello analysis reveals international humanitarian law requirements for the use of force were satisfied, the aforementioned jus ad bellum analysis concluded that those requirements for the use of force were not satisfied. Therefore, while it may be intellectually interesting to consider questions of jus in bello in determining the legality of the air strike, such considerations are ultimately rendered irrelevant given the previous jus ad bellum analysis.
CONCLUDING REMARKS AND LOOKING TO THE FUTURE
The US air strike in Syria is likely not explicitly legal under current international law. Although the strike meets many of the principles of jus ad bellum and jus in bello, there was no UN Security Council resolution authorizing the action, jeopardizing the legality of the strike under the just cause principle of jus ad bellum. It is also dubious that the use of chemical weapons in Syria represents a large enough genuine threat to the United States that it could invoke Article 51 of the UN Charter. While the air strike may not be strictly legal, however, we may conclude that it is ultimately justified if we are to believe the United States was acting in the collective self-defense of Syria’s neighbors or if we accept the merit of the emerging international norms of a responsibility to protect and a duty to prevent. It must be stressed that since this is only an emerging norm and not codified law, the air strike is still in violation of international law. That said, the Trump administration is likely to face few legal repercussions in the wake of the missile strike in part because of these normative justifications. Additionally, the US air strike in Syria further emphasizes the growing concern that the current international legal system is ill-equipped to handle such “justified” but technically illegal uses of force. If anything, the debate on the legality of the US air strike in Syria demonstrates that further efforts to close the gap between emerging norms in international law and the current laws of war are necessary.
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