USS Belmont (AGTR-4/AG-167) was the first of two Belmont-class technical research ships,, acquired by the U.S. Navy in 1963 and converted for the task of conducting "research in the reception of electromagnetic propagations". She was originally built during World War II as a Victory cargo ship named SS Iran Victory by the War Shipping Administration's Emergency Shipbuilding program under cognizance of the U.S. Maritime Commission.
USS Belmont underway in the late 1960s
Technical research ships were used by the United States Navy during the 1960s to gather intelligence by monitoring, recording and analyzing wireless electronic communications of nations in various parts of the world. At the time these ships were active, the mission of the ships was covert and discussion of the true mission was prohibited. The mission of the ships was publicly given as conducting research into atmospheric and communications phenomena. Their designation was AGTR – Auxiliary, General, Technical Research – but it was more or less an open secret that this was a euphemism and they were commonly referred to as "spy ships".
USS Liberty spy ship
USS Pueblo
USNS Private Jose F. Valdez