Not ITAR, apparently ATF:
“A3. An alien admitted to the United States under a nonimmigrant visa is not prohibited from purchasing, receiving, or possessing a firearm if the alien falls within one of the following exceptions: (1) is in possession of a hunting license or permit lawfully issued by the Federal Government, a State, or local government, or an Indian tribe federally recognized by the Bureau of Indian Affairs, which is valid and unexpired; (2) was admitted to the United States for lawful hunting or sporting purposes; (3) has received a waiver from the prohibition from the Attorney General of the United States; (4) is an official representative of a foreign government who is accredited to the United States Government or the Government’s mission to an international organization having its headquarters in the United States; (5) is en route to or from another country to which that alien is accredited; (6) is an official of a foreign government or a distinguished foreign visitor who has been so designated by the Department of State; or (7) is a foreign law enforcement officer of a friendly foreign government entering the United States on official law enforcement business. “
Here’s how the Feds could charge them with possession.
Constructive possession is a legal theory used to extend possession to situations where a person has no hands-on custody of an object. Most courts say that constructive possession, also sometimes called “possession in law,” exists where a person has knowledge of an object plus the ability to control the object, even if the person has no physical contact with it (United States v. Derose, 74 F.3d 1177 [11th Cir. 1996]).