The news that Syrian troops are providing support to ISIL may add a dangerous new twist to the US campaign against the terrorist group and open up legal authority for the US to fight Syrian Dictator Bashar al-Assad’s forces directly. On June 2, the US Embassy in Syria tweeted, “Reports indicate that the regime is making air strikes in support of ISIL’s advance on Aleppo, aiding extremists against Syrian population.” That post was quickly followed by another saying, “With these latest reports, Asad [sic] is not only avoiding ISIL lines, but, actively seeking to bolster their position.”

This is hardly the first time we’ve heard of Assad’s military working with the Islamic State. The Syrian dictator’s jets have reportedly bombed Syrian rebel positions to aid ISIL since January 2014. To be fair, there are also plenty of reports of Assad’s forces fighting ISIL. Indeed, the lack of information about the relationship between Assad and ISIL may be one of the toughest problems for American policymakers struggling to come up with a plan to defeat the terrorist organization.

But if Assad’s military is helping ISIL, two sets of legal questions arise about whether the US can go after Assad’s forces directly. The first deals with US domestic law and the White House’s justification for military operations against ISIL. 

If the 2001 AUMF authorizes US military operations against ISIL, does the Syrian government’s aiding ISIL bring Assad and company under the 2001 AUMF as an “associated force” of the al Qaeda offshoot? Furthermore, what does it mean that Damascus is aiding ISIL while the group takes over vast swaths of Iraq? The White House has said the 2002 AUMF that backstopped the 2003 Iraq war provides additional legal cover for its campaign against ISIL thanks to provisions permitting US military operations to maintain the stability of Iraq. Would Assad’s affirmative support of ISIL inside Syria go beyond the point of being unwilling and unable to stop the threat that ISIL poses to Iraq and count instead as complicity in promoting that threat?

The second set of legal questions goes to matters of international law and the use of force in self-defense. Do Assad’s airstrikes turn his government essentially a co-belligerent with a group the US government has deemed a threat to both American national security and the stability of Iraq? Think back to the 2001 US invasion of Afghanistan to overthrow the Taliban. The US did so on the grounds that the Taliban gave al-Qaeda a safe haven from which to attack the US. Last summer, ISIL arguably used Syria as a stable base to launch its invasion of Iraq. That came after Assad’s air force reportedly helped the terror group eliminate rivals inside Syria. Evidence that Assad is playing a similar role in protecting ISIL to the same extent the Taliban did with al-Qaeda doesn’t yet exist, at least not publicly. However, the door may be open to this sort of argument on international law grounds if reports of the Syrian air force supporting ISIL become routine.

Finally, what does it mean if the Syrian government is aiding ISIL in fighting rebel groups that the United States is training and equipping to fight the terrorist group? Could this provide the US with the justification to conduct operations against Assad’s military if he turns its guns on those “moderate rebels” with whom the US is working?

The broader question of whether the US can defend these moderate groups against Assad is debate at the White House, according to a recent exchange between Senate Foreign Relations Committee Chair Bob Corker (R-Tenn.) and State Department Legal Adviser nominee Brian Egan.

Senior American military officials have told lawmakers they do not have the authority to strike Assad regime forces that attack Syrian rebel groups that the United States is training and equipping in their fight against ISIL. However, during a Senate Foreign Relations Committee hearing last month, Corker asked Egan if the US had the authority to defend rebel groups against attack by Assad. Egan noted that the US has the authority to defend the rebels against attacks from both ISIL and the al-Qaeda affiliated al-Nusra group but that the option to protect rebels from Assad forces is “under policy review.”

Here’s Corker’s specific question:

Martin Dempsey, Ash Carter and several witnesses who came before us said they do not have the authority to defend against Assad if the train and equip people, that are not our folks, they’re not part of our coalition they’re people we’re training in Syria to deal with both ISIS … and there may be another alleged program against Assad, but they actually say they don’t have that authority. But you’re actually saying that you believe we do have that authority to defend them against barrel bombs from Assad? They said they hadn’t sought that authority and there’s actually an internal debate right now within the administration as to whether to seek that authority. … The Syrian opposition train and equip group, we don’t have that authority, would you agree?

Here’s Egan’s final answer:

Egan: We would have the authority to conduct military operations against ISIL and al-Qaeda under the same rationale that we do to conduct direct operations against those groups. I think the question of our authority to use force against the Assad regime is a more difficult question, that you’re correct sir, that is one that’s under policy consideration within the administration right now.

Corker: To defend the very people that we’re training to go in and be on the ground?

Egan: That is correct.

The Obama administration claims to be fighting ISIL under the auspices of a war against al-Qaeda, its offshoots, and its affiliates. By having his jets serving as ISIL’s air force, Assad may be positioning himself dangerously close to joining ISIL in combat against the rebel forces that the US is training to fight ISIL. All of this may draw Assad into American crosshairs. That may be true not only as a matter of military strategy but also as a matter of greater legal authority for the Obama administration to act.