Israel will send their own security forces, acting as though they could possibly help US; and from there, they can steer the investigation to point toward Iran (or Syria or Lebanon, depending on who they want to genocide this week). If these bombers are, as I suspect, Israeli agents, they will also try to cover their tracks. Watch and wait. Truly, though, they overplayed their hand with their attack in Bulgaria; nobody believed them when they tried to pin it on "Hezbollah". They were a laughingstock after that.
Aden hotel used by Yemen goverment hit by grenade (Reuters)