1. I’ve been thinking more about this. As a matter of the jus ad bellum, Oona is unequivocally correct. There is no conceivable way to describe #Fakhrizadeh’s work as posing the threat of an imminent armed attack on #Israel. Not even the US accepts the legality of preventive SD. https://twitter.com/oonahathaway/status/1332428585982976004

2. The (independent) jus in bello question is more difficult. If it is true Fakhrizadeh was a senior officer in the Islamic Revolutionary Guard Corps, he was a lawful target at any time and anywhere in an IAC, because the IRGC is formally part of #Iran’s armed forces.

3. The real question, then, is whether Iran and Israel are engaged in an IAC. If you accept the “first shot” theory, the answer is yes — the mere fact Israel killed a member of another state’s armed forces was sufficient to trigger IHL and to make IHL apply to the first shot.

4. I reject that theory — without importing an intensity requirement into the definition of IAC. In my view, although any first shot triggers IHL, IHL only applies to subsequent shots. That, to me, is a matter of simple logic — even if many disagree. (See http://opiniojuris.org/2020/01/20/soleimani-and-targeted-killings-of-enemy-combatants-part-ii-geneva-law-versus-hague-law/)

5. If I’m right, IHL did not apply to Israel’s killing of Fakhrizadeh and thus, as a matter of IHRL, the killing was unlawful. If others are right, IHL did apply and Fakhrizadeh's killing was lawful. (Though still unlawful under the jus ad bellum.)

6. To me, this illustrates the problem with the first-shot theory: it means a state can *never* violate the right to life by killing a member of another state’s armed forces, even if the two states have never engaged in hostilities. The mere act of killing means IHL permits it.

7. In short: in my view, Israel’s killing of Fakhrizadeh violated (1) Iran’s sovereignty (jus ad bellum) and (2) Fakhrizadeh’s right to life (because IHRL applied, not IHL). If you accept the first-shot theory, you can believe (1) but not (2).

PS: apologies to anyone who kindly liked either of the last two tweets. I rewrote tweet 6 to be more accurate.