Re: "Any assassination could be seriously damaging to this nascent diplomacy"
"No, it has to be the US. We like guns and we like killing people with them. In fact, we like shooting people so much that we do it to each other."
True enough, we do. I have an M1911A1 sitting two feet from me.
In a locked safe.
With the keys inconveniently far away from me, as I so rarely go into that safe.
Seriously though, let's review some facts.
He was found in a remote wooded area. Shot twice in the chest.
OK, so he went along with or met his killer in the woods.
Yeah, a US assassin would arrange an appointment in the woods with him. Yep!
Israeli methods also don't quite match.
Sorry, folks, the situation and method suggests something domestic to Iran. Either a power struggle or more likely, a personal matter that a meeting was privately arranged for in the woods to settle.
Only, not in the manner the man expected.
Because, Iran is loaded with Iranians. Iranians are human, just like the lot of us. Every one of our nations has plenty of people who commit murder for a bewildering number of reasons.
No clue why. I'd not shoot an armed intruder here.
Since that safe is small, I'd hit him over the head with it.
Then, greet him more politely with a swordstick in one hand and my old bayonet from the Army in the other, standing on his gun.
Assuming that foot long safe didn't leave him with a depressed skull fracture.
But, I'm a professionally trained, retired US Army SF medic. I'll happily call 911 for him.