If they put it on a drone, it won't make it to Tel Aviv. They'll either smuggle it in, chancy at best, or they'll launch a bunch of Scud type rockets, one or more of which will contain the magic pea.
Question: You're the Prime Minister of Israel. It is August 22nd. If your military detects a "scud-type" vehicle launched from Iran headed toward Israel, you then try to shoot it down with your ABMs (the Patriots provided by the good old USA).
If you are successful and shoot it down, do you assume the scud was carrying a nuke, and respond accordingly?