At the Just Security blog, Jennifer Daskal, Ashley Deeks and Ryan Goodman discuss the international law framework for America's strikes in Syria. They comment:
According to a letter submitted by the United States to the United Nations on Tuesday, the Administration is justifying the strikes against ISIL as a lawful exercise of collective self-defense of Iraq. The letter then goes on to state that the strikes against the Khorasan Group “address terrorist threats that they pose to the United States and our partners and allies.”
As the letter suggests, the legal justification for strikes against ISIL is presumably not the same as that for strikes against Khorasan. The following unpacks some of the key differences. . . .
The U.S. government received a letter from the Iraqi government explicitly asking for U.S. help in the fight against ISIL, thus supporting a claim of collective self-defense. According to the U.S. notification to the United Nations, Iraq has specifically requested that the United States lead international efforts to strike ISIL sites inside Syria to suppress continuing attacks on Iraq and protect Iraqi citizens. Under a theory of collective self-defense, the United States is assisting Iraq in responding to the direct and ongoing threat posed by ISIL; the threat stems in part from ISIL forces in Syria; and Syria is either unable or unwilling to quell the threat, thereby justifying an incursion into Syria’s territory. . . .