"We are deeply disappointed and troubled by the presence of Iranian military officials and reportedly Iran's Islamic Revolutionary Guard Corps officers at the Doha Defense Show in Qatar," said State Department spokesman Ned Price.

"We utterly reject their presence at the show and its maritime defense exhibit," Price said, calling Iran "the biggest threat to maritime stability in the Gulf region."

Iran had a large display of models of its aircraft, missiles and other military equipment at the show, which also featured a visit by naval vessels of different countries and displays by some of the world's leading military shipbuilders.

Qatar is a close US ally, hosting the regional headquarters of the Pentagon's Central Command at the al-Udeid Air Base, and permitting regular shore visits by US naval vessels patrolling the Gulf region.

The US maintains strong sanctions on doing business with the Iranian military and particularly the Revolutionary Guard Corps, which Washington has officially dubbed an international terror organization.

"Transactions related to Iranian weapons are generally sanctionable under multiple US authorities, including sanctions related to terrorism and weapons of mass destruction," Price said in a statement.