The Legality of the United States’ Strike on Soleimani

On January 2, 2019, the United States carried out a drone strike at Baghdad airport in Iraq in which Qassem Soleimani, a high-level Iranian military leader, was murdered.  This post will analyze the legality of this particular United States’ use of force under international law as well as under U.S. domestic law.  Moreover, this post will discuss (negative) policy implications of this strike.

International Law

By launching an air strike on the territory of a sovereign nation (Iraq), which targeted a top-level military official of another sovereign nation (Iran), the United States used force against two other sovereign nations.  Such use of force is prohibited under Article 2(4) of the United Nations Charter, and the United States thus violated its international law obligations under the Charter, unless the United States can demonstrate that the military strike was conducted pursuant to a Security Council authorization or in self-defense.  In this case, the United States acted alone, without seeking Security Council approval.  Thus, under international law, the only way that the United States could justify the drone strike and the resulting killing of Qassem Soleimani is through self-defense.

The traditional law of self-defense, as reflected in Article 51 of the United Nations Charter, allows a state to use force in self-defense if it has been subjected to an armed attack.  Moreover, the use of force in self-defense must respect the requirements of necessity and proportionality.  In this instance, even assuming that Soleimani was planning activities which would have been harmful to the United States’ national security interests, the United States had not suffered an armed attack by Soleimani/Iran and cannot rely on the traditional law of self-defense.  More recently, scholars (for a good recap of the law of anticipatory and pre-emptive self-defense, see here and here) and some states (United States in particular) have advanced more aggressive variants of self-defense, including preventive self-defense, pre-emptive self-defense, and the “unable or unwilling” standard.  The George W. Bush administration argued that force could be used in self-defense in a pre-emptive manner, against both terrorists as well as countries which harbor terrorists.  The strike against Soleimani could potentially be justified under pre-emptive self-defense, especially if evidence demonstrated that Soleimani was engaged in activities which posed a threat toward the United States.  However, pre-emptive self-defense is not a widely accepted interpretation of the international law of self-defense; it is not part of treaty or customary international law; even subsequent United States’ administrations have adopted different views on self-defense.  Thus, pre-emptive self-defense remains a controversial interpretation of the international law of self-defense.  The Obama Administration adopted a different approach by arguing that the United States could use force in compliance with the international law of self-defense against a state which was unable or unwilling to control non-state actors operating from within its territory, if such actors posed an imminent threat to the United States. Under the Obama Administration view of the right of self-defense, the United States’ strike against Soleimani cannot be easily justified because, even if Soleimani posed an imminent threat to the United States (it remains to be seen whether Soleimani was presently engaged in activities which would have posed an imminent threat against the United States), he was not a non-state actor, but rather an Iranian military official. It is thus questionable that the strike was lawful under the Obama Administration paradigm of self-defense paradigm.  Finally, the United States could possibly claim that it was acting in collective self-defense pursuant to Iraq’s request for help- that Iraq had requested assistance from the United States in acting against Soleimani/Iran.  As of now, there is no evidence that this was the case.  The U.S. troops were in Iraq to lend support in the fight against ISIS, and it appears that the United States launched this attack without Iraq’s knowledge or approval.  In fact, in response to the Soleimani strike, the Iraqi Parliament has voted a resolution which would expel U.S. troops from Iraq.  Thus, the collective self-defense argument has no merit for now.  The only way in which the Soleimani strike can be possibly justified under self-defense would be through the Bush Doctrine/preemptive self-defense.  As argued above, pre-emptive self-defense is not part of well-accepted international law as of today, and the Soleimani strike is illegal under international law.

Domestic Law

Under United States’ law, the President can use force against another sovereign nation pursuant to his constitutional authority as Commander-in Chief, or pursuant to specific congressional authorization to use force.  Congress has not authorized the president to use force against Iran.  Congress did authorize the president to use force against those who planned the September 11 attacks in 2001 (2001 AUMF), as well as to use force against Iraq in 2002 (2002 AUMF).  It is very difficult to link Soleimani to Al Qaeda/Taliban terrorists who planned the 9/11 attacks.  It is equally difficult to claim that Soleimani was operating in Iraq, and that the strike against him would somehow support the U.S. troops present in Iraq pursuant to the 2002 AUMF. Thus, the 2001 and 2002 AUMFs did not authorize the president to use military force in this particular instance.  The relevant question therefore becomes whether the president had inherent constitutional authority to act.  Although considerable debate exists about the scope of presidential power regarding the use of military force without congressional authorization, the executive branch, through several Office of Legal Counsel memoranda, has argued that the president has the authority to use force when: 1) there is an important national security interest in doing so; and 2) the use of force falls short of “war” in the traditional sense.  The executive branch has thus advanced the view that “military operations will likely rise to the level of a war only when characterized by ‘prolonged and substantial military engagements, typically involving exposure of U.S. military personnel to significant risk over a substantial period.’” Pursuant to this view, the executive branch has opined that the U.S. military activities in Haiti in the 1990s, the military strikes in Libya in 2011, as well as in Syria in 2018, did not cross the “war” threshold.

Moreover, the War Powers Resolution of 1973 imposes an additional limitation on the president’s authority to conduct military operations without explicit congressional approval.  The War Powers Resolution specifies that the president may introduce U.S. armed forces into hostilities only if there is a 1) declaration of war; 2) specific statutory authorization; or 3) a national emergency created by an attack against the United States.  The War Powers Resolution also requires that relevant military operations be terminated after a defined period of time (60 days), unless Congress specifically authorizes further military action, as well as that the president report to Congress within 48 hours of engaging in hostilities.  In this instance, the Trump Administration has actually provided a classified report to Congress under the War Powers Resolution, two days after the drone strike which killed Soleimani.  As of now, the report is classified and it is impossible to know what type of rationale the administration has provided to Congress. Presumably, the Trump Administration believes that the strike falls within the War Powers Resolution limitations on presidential authority to conduct military attacks as the Administration has provided a post-strike report to Congress.

In light of the above, the strike against Soleimani would be legal under U.S. domestic law only if the strike was in the U.S. national security interest, if the strike did not constitute “war,” and if the strike did not lead U.S. troops into “hostilities” under the War Power Resolution.   It is debatable whether the strike was in the U.S. national security interest now – although many experts agree that Soleimani had been a threat to the United States, it is unclear if he was presently involved in planning attacks against the United States.  Moreover, it is uncertain whether the strike falls short of “war.”  In addition to the executive branch test mentioned above (“prolonged and sustained military operations”), Office of Legal Counsel memoranda have suggested that the use of force may constitute “war” if such force is used against another sovereign nation without such nation’s consent, and if there is a high likelihood of escalation.  In this instance, the relevant question to ask is whether the strike is likely to lead U.S. troops to enter prolonged and sustained military operations with a high likelihood of escalation (the strike was clearly conduct4ed without Iraq’s consent).  If the answer to this inquiry is positive, then the president’s action would be illegal under U.S. law.  Finally, it is unclear whether the military strike against Soleimani constitutes a “hostility” under the War Powers Resolution.  The Obama and the Trump administrations have taken the position that providing aerial refueling and intelligence support to the Saudi-led coalition in Yemen falls short of introducing U.S. troops into “hostilities.” It may be argued that the killing of another nation’s military leader is an action much more likely to lead U.S. troops to enter “hostilities” than an action conducted to provide aerial refueling or intelligence support.  In sum, it is debatable whether the military strike which killed Soleimani is legal under domestic law.  In order to reach this determination, one would have to conclude that the strike was in the U.S. national security interest, that it did not amount to war, and that it would not lead U.S. troops to enter into hostilities.  In light of the ongoing crisis with Iran, and the fact that Iran is state with a strong military, as well as with developing nuclear technology, it is likely that the strike will lead to an escalating military conflict.  Thus, it is more than reasonable to conclude that the strike was not conducted pursuant to domestic legal authority, because the president did not seek requisite congressional authorization and did not have inherent constitutional authority to act.


Finally, even assuming that the strike was lawful under international and domestic law, the strike did not amount to good policy.  First, the strike may portray the United States as a rogue actor in the Middle East, willing to carry out assassinations against those whom its perceives as enemies.  This image of the United States may limit its ability to build strategic alliances with other countries in the Middle East as well as with other global partners.  Second, the strike may provoke revenge and retaliation by Iran.  Iran could attack Americans in the Middle East, could pursue attacks or other aggressive actions against Israel, an important U.S. ally, and could act through various proxies to destabilize the Middle East.  Iran will likely  re-initiate its nuclear weapons development programs, as it has already announced that it is abandoning the Nuclear Agreement which it had signed with the United States and several European countries; this will pose an additional threat in the region.  Third, the strike has already caused a backlash from other countries and non-state/terrorist actors.  As mentioned above, the Iraqi Parliament has voted to expel U.S. troops from Iraq.  United Nations Secretary-General Antonio Guterres has expressed “deep concern” over the U.S. strike against Soleimani; Russia has condemned the strike, and several Americans were killed in a terrorist attack in Kenya.  Fourth, it is unclear how the strike furthers United States’ national security and foreign policy.  As mentioned above, there is no credible information to suggest that Soleimani was engaged in present-day terrorist activity against the United States, and his elimination does not protect the United States any further, nor does it advance any particular foreign policy in the Middle East.  In fact, the strike is likely to cause conflict in this already volatile region and to potentially drag the United States into another war.  In sum, the strike is illegal under international law, very likely illegal under domestic law, and definitely bad policy.