A nuke in a random container on a ship filled with thousands of them, owned by a bunch of shell companies, combined with the fact that the evidence gets blown up in the process...
Quite a bit harder to track to a source than "hey look a rocket launched from Iran".
Not really. It’s a fairly short list of organizations with the means and the motivation. If you’re already spying on them it’s not hard to pick up on changes in communication, movements or even catch them red handed on a recorded line.
An attack like that would also be carte blanche to nuke whoever the hell you wanted — that wasn’t themselves a nuclear power that could survive the volley — in retaliation.
