Donald Trump has been widely criticized for announcing a military withdrawal from Syria. However, the American legislation imposes clear restrictions to further engagement in the war-torn country.

By Michael Goodyear

On December 19, 2018, President Donald Trump declared victory over the Islamic State (IS) and ordered the withdrawal of all US forces from Syria. This move has been disparaged for betraying US allies, starting with the Kurdish Syrian Democratic Forces (SDF), but the legal constraints on the president’s war powers leave the American government little choice if IS is indeed defeated.

The situation in Syria

The US military became directly involved in Syria in September 2014. The US mission had a clear purpose: stop the territorial expansion of IS. The group emerged from Al-Qaeda in 2006 and initially operated as a terrorist organization in the same fashion, before developing into a territorial state. At its height in 2015, IS controlled nearly half of Syria and a significant part of northern Iraq.

Propaganda image of “ Islamic State fighters going into battle ” from Dābiq Magazine of  the Islamic State, Issue #15, July 2016

Since mid-2015, IS has been gradually pushed back by a variety of coalitions in Syria and Iraq, losing all of its major cities in 2017, including its capital, Raqqa. Iranian President Hassan Rouhani and Russian President Vladimir Putin both declared victory over IS in November 2017. While only a few pockets of resistance fighters remain along with an online shadow state (referred to as the Cyber Caliphate), IS, as a territorial country, is severely weakened, albeit not entirely dead. In recent years, Syria has been split between three groups: the regime of Bashar Al-Assad, a nebula of anti-government forces, and the Kurdish-dominated SDF. Each of these three powers has significant foreign backing, with Iran and Russia supporting Assad, Turkey supporting some of the anti-government forces, and the US supporting the Kurds. If the US were to stay in Syria, it would be to engage in military operations in this three-party war, which would require a separate legal justification from fighting the Islamic State.

The development of US law of war

The justification for US military engagements is based on an accumulated body of law that has limited the way the executive branch can conduct military operations overseas. The first major legal case on the exercise of war powers by the president was the Prize Cases in 1863. The Supreme Court concluded that the executive branch may act without Congressional approval to authorize defensive actions, granting unilateral response capability to the president in the event of an attack on the US.

Following the Prize Cases, there was a long gap without any significant changes to the president’s authority to engage in military action. In 1973, however, Congress redrew the map on the law of war by passing the War Powers Resolution, in response to the Vietnam War. This legislation severely limited the ability of the president to unilaterally engage in war by only authorizing war if (1) there is a declaration of war; (2) there is specific statutory authorization (Congress gives the president permission); or (3) a national emergency is created by an attack on US territory, possessions or forces. The third category is effectively the holding of the Prize Cases, while the first two require Congressional approval. If the president nevertheless does engage in hostilities, he is subjected to several reporting requirements to Congress. The use of military force is also capped at an initial 60 days unless Congress authorizes an extension or declares war.

Despite President Richard Nixon’s plea that the War Powers Resolution was unconstitutional for limiting the President’s powers, the law stuck. The reach of the War Powers Resolution, however, has been restricted by the Obama administration. Obama’s Office of Legal Counsel (OLC) developed a three-prong approach to justifying its military engagements. First, it followed the text of the War Powers Resolution to see if there was a grant of military authority by Congress. Second, it determined that the primary authorization under the War Powers Resolution did not apply to operations that were in the “national interest” and were “not war.” Finally, the 60-day pull-out provision of the War Powers Resolution was determined to only apply if the operation rose to the level of “hostilities” (understood as a lower degree of military involvement than outright war).

Congressional authorization for military operations in the last two decades has been largely grounded in the 2001 and 2002 Authorizations for Use of Military Force (AUMF). The 2001 AUMF authorized the president to fight anyone who was a part of or substantially supported the groups that carried out the 9/11 terrorist attacks, namely Al-Qaeda and the Taliban, which translated into the intervention in Afghanistan. The 2002 AUMF, on the other hand, authorized the president to take military action against Iraq in the defense of US national security.

The “national interest” and “not war” arguments were developed by the Obama OLC in 2011 to justify US airstrikes in Libya. Congress had not provided authorization for the president to engage in military operations in Libya and it was not a defensive action, so airstrikes would seemingly not be authorized under the War Powers Resolution. However, the OLC reasoned that the War Powers Resolution only restricts the ability to engage in “war,” which was not the case here. The OLC then restricted the definition of war to “prolonged and substantial military engagements with significant exposure of military personnel or risk.” To this “not war” condition it also added a “national interest” requirement. While in theory this restricted the extent of the carve-out the OLC was creating, it actually allowed the president to conduct any military operation as long as it did not rise to the level of “war.” National interest, in the case of Libya, was defined as preserving regional stability and bolstering the credibility of the United Nations Security Council – which, in the eyes of the US (as opposed to Russia and China), had authorized the attacks on Libya – as well as designating NATO to carry out the attacks.

However, even if the military operation did not rise to the level of “war,” it was still subject to the 60-day pull-out requirement of the War Powers Resolution. To get out of this requirement, Harold Koh, the legal advisor for the State Department, stressed the scope of “hostilities,” the term used for the 60-day pull-out requirement. Koh argued that if the military operation did not rise to the level of “hostilities,” there was no 60-day restriction. This distinction looked at whether the mission was limited, whether the risk of escalation was limited, whether the exposure was limited, and whether the choice of military means was narrowly constrained. If these four factors were met, the military operation would not qualify as “hostilities” subject to the 60-day pull-out provision. Koh initially used this argument in testimony in front of Congress to justify US military involvement in Libya extending beyond 60 days. He stated that the mission was limited since its purpose was only to support NATO coalition forces. The exposure of armed forces was also limited since there were no US ground forces and only airstrikes were used. The risk of escalation was limited as well because, again, no ground forces were used. Finally, the use of a few highly targeted airstrikes constituted only limited military means.

Harold Koh speaking at a UN conference in Geneva, in 2009 (© Eric Bridiers / Wikimedia Commons)

Justification to fight the Islamic State

In the case of IS, the Obama administration initially authorized individual attacks in a 2014 OLC Opinion on the basis of “national interest” and under the condition that these limited attacks did not rise to the level of war. The national interest in the 2014 strikes against the Islamic State was defined as the protection of Americans, the assistance to an ally (Iraq in this case) and the prevention of a humanitarian crisis. Initially, the US only engaged in limited drone strikes comparable to the type of warfare used in Libya.

It quickly became clear, however, that IS was not just any radical Islamist terrorist organization, but also a powerful territorial state. The US needed to commit more troops and supplies if it were to defeat the group, hence weakening the argument that the operation was to be limited and would not raise the level of “hostilities” or “war.” Since IS originally emerged from Al-Qaeda, the Obama administration fell back on the 2001 AUMF. This provided an effective justification for the military engagement in Syria over the past four years.

No authorization to stay

If the executive branch admits that IS has been destroyed in Syria, as President Trump announced last month, there cannot be a legal authorization for the president alone to keep US troops in the country. Even if Trump has since contradicted himself and other members of his administration have also said that IS was still active, the overarching rationale behind the announced withdrawal from Syria still holds. In short, if IS still exists, operations could continue to be legitimized under the 2001 AUMF, but an official statement by the commander-in-chief that the enemy has been defeated strongly undermines this argument. In any case, assisting Kurdish allies does not provide a standalone justification, as was implied by President Trump’s national security advisor, John Bolton.

US National Security Adviser John Bolton with Secretary of Defense James Mattis, in 2018 (Source: Archives of the U.S. Secretary of Defense / flickr)

The Trump administration could have very well not thought out the foreign affairs law surrounding the withdrawal. However, since it constitutes US domestic law, the Trump administration – and any past or future administration for that matter – is legally held to this standard. Maintaining these established principles for the use of force also benefits the US in foreign relations, since it makes the US a more predictable international actor.

Overall, three main legal arguments call for the withdrawal of American involvement on the ground in Syria. First, unlike IS, the three current factions in Syria are not related to Al-Qaeda or the Taliban. Therefore, the 2001 AUMF cannot apply to them. Congress has also granted no further authorization for use of force in Syria. While small terrorist cells still exist in the country, they are scattered and do not currently constitute major players. Interfering in a foreign country to hunt down minor terrorist groups would overstep Congressional authorization and violate international borders, creating a situation reminiscent of the American hunt for Pancho Villa in northern Mexico (1916-17).

Second, further military operations in Syria would almost certainly rise to the level of war. While the 2014 OLC Opinion listed assisting allies as a national interest, which could justify assisting the Kurdish SDF, that justification would only work assuming that the operations would not rise to the level of war. The US has engaged in airstrikes against the Assad government in Syria since 2017, and it could be argued that those did not develop into larger military engagements. However, any further military support for the SDF on the ground could trigger a larger conflict in the region. This is especially true since Turkey has vehemently led the anti-government forces in the war against the SDF. Amid an already 8-year long civil war with no end in sight, there are dangerous risks of a prolonged and substantial military engagement in Syria due to the involvement of Iran, Russia and Turkey.

Kurdish fighters in Syria(© Kurdishstruggle / flickr)

Finally, even if the Trump administration felt that they could justify further operations under the 2011 OLC framework, it would still be subject to the War Powers Resolution restrictions, including the 60-day limit on the campaign. This is because the operation would likely not be limited in its scope, hence excluding the legal theory developed by Koh to circumvent the War Powers Resolution.

The Trump administration could attempt legal acrobatics to create a new justification, like the Obama administration did in Libya. However, the current government has largely followed the pre-existing procedures on foreign affairs law. Furthermore, while Obama selected legal academics such as Koh, who were instrumental in working around existing frameworks and theorizing new ones, the Trump administration is still a tangled mess. Half of the top jobs in the State Department are still unfilled, and his administration has been characterized by regular turnovers and instability. While the hypothesis of this administration creating a new legal doctrine to authorize a war in Syria is not impossible, it remains extremely unlikely.

Without Congressional approval, the Trump administration cannot justify continued military operations in Syria after the proclaimed defeat of IS. It also cannot do so solely to support Kurdish allies on the ground. Since the legal loopholes developed by the Obama administration OLC and Koh do not apply to the current situation, Congressional approval will be necessary under the War Powers Resolution to legally justify further military operations in Syria. In the current state of American politics, this scenario is at best improbable.

Cover Picture: the USS Carl Vinson in the Arabian Gulf to support military operations in Syria in 2014, © U.S. Navy / flickr