In their post earlier today, Jack Goldsmith and Oona Hathaway argue that the Trump administration had no apparent domestic or international legal authority for last night’s air strikes against Syria. I had similarly questioned the legal basis, especially the international law basis, for the U.S. air strikes against Syria in April 2017. I would offer these additional thoughts now:

Domestic Law Basis. While I agree with Goldsmith and Hathaway that neither the 2001 nor the 2002 AUMF provides a statutory basis for the use of force in response to Syria’s use of chemical weapons, I am more comfortable that the president had constitutional authority to order the strikes because there is a plainly compelling national interest to deter Syria and other nations from using chemical weapons against their own people. In his War Powers report submitted after the April 2017 strike, the president stated that, “I directed this action in order to degrade the Syrian military’s ability to conduct further chemical weapons attacks and to dissuade the Syrian regime from using or proliferating chemical weapons, thereby promoting the stability of the region and averting a worsening of the region’s current humanitarian catastrophe.” When the president submits his War Powers report relating to yesterday’s strike (which is due within 48 hours of the strike), I am confident that he will cite a similar rationale (although I hope he might provide more detail). Goldsmith and Hathaway overstate the case to say that supporting this rationale would allow a president to use force whenever he sees fit. Although it is always preferable to have congressional authorization for the use of military force, it was not legally necessary under these circumstances.

International Law Basis. As I noted in my post in response to the April 2017 strike, the U.S. does not have clear authority under international law to use force in response to Syria’s use of chemical weapons. Unlike Britain, the United States has never recognized a right of humanitarian intervention under international law. There are certainly arguments that states should have such a right, and even that a right of humanitarian intervention existed before the U.N. Charter, but it is difficult to contend that international law currently recognizes such a right. The best the Trump administration may be able to do is to argue that its limited use of force (in both 2017 and 2018) was “justified” (even if not strictly lawful) based on the specific facts of the situation in Syria and that other avenues had been exhausted. Indeed, this appears to be the tack the State Department has chosen: Ambassador Nikki Haley said earlier today that “These strikes were a justified, legitimate and proportionate response to the Syrian regime's continued use of chemical weapons on its own people” (emphasis added).

What More the Trump Administration Should Do. It is regrettable that President Trump has made no reference to domestic or international law in his oral statements regarding the U.S. military strikes against Syria in 2017 or 2018. Unfortunately, these omissions may reflect that he has little regard for (or even awareness of) the legal constraints on his actions as president. His senior national security advisers—Secretary of Defense James Mattis, Acting Secretary of State John Sullivan, CIA Director (and Secretary of State-designate) Mike Pompeo, National Security Advisor John Bolton, Attorney General Jeff Sessions, and Counsel to the President Don McGahn (the last five of whom are lawyers)—should all urge the president to act consistent with, and specifically refer to, the legal rules governing use of force.

In the absence of statements by the president himself, senior administration officials (both policy officials and lawyers) should provide more detailed explanations regarding the domestic and international law basis for the Syria strikes. And in the absence of a clearly articulable international legal basis, administration officials should explain in more detail why the strikes were “justified” and “legitimate.”

It is not necessary or appropriate for the administration to produce to Congress its own internal legal memoranda regarding the use of force against Syria, as Sen. Tim Kaine has requested, but I agree with Kaine that the administration still owes Congress a detailed legal explanation. It is also important that the United States explain the basis for the Syria strikes to the rest of the world. As I said in testimony before the Senate Foreign Relations Committee last December regarding legal rules governing the use of force: “When the United States uses military force, especially under controversial circumstances, it should explain the legal basis for its actions. When the United States does not do so, it appears to act lawlessly and invites other countries to act without a legal basis or justification."