The U.S. Defense Department says Iranian fighter jets fired on an unarmed U.S. drone over international waters in the Persian Gulf last week.

Pentagon spokesman George Little says the unmanned Predator was on a routine classified surveillance mission November 1. Little said the plane did not enter Iranian waters, was not hit and returned safely to its base. The Pentagon said this is the first time Iran has fired on a U.S. drone.

Little says the United States informed Iran that it will continue surveillance operations over the Persian Gulf in line with a longstanding policy and commitment to security in the region.

Little did not comment on what response the Pentagon plans to make to Iran, but said both military and diplomatic options are on the table to protect U.S. assets.

The Pentagon usually does not comment on classified missions. But Little says the report of the attack on the drone was leaked. He calls this unfortunate.