Unlikely they would test so close to the Straits.
Far more likely they would test in the interior of
the country (Dasht-e-Kavir) or in conjuction with
the Chinese.
USAF can sample the air; detect residue if this in fact happened.
“USAF can sample the air; detect residue if this in fact happened.”
Except for the fact that the prevailing winds blow from the gulf over Iran. The AF would have to fly over Iranin airspace to make that detection and it would give the entire width of the country for it to disipate.