The US Navy has confirmed a wreck found on the bottom of the Java Sea is the USS Houston, a cruiser sunk by the Japanese in World War Two.
The wreck is the final resting place of as many as 700 US sailors and marines, the Navy said.
US and Indonesian divers discovered evidence that pieces of the hull and unexploded ordnance had been removed.
The site is a popular underwater dive spot, and officials are co-ordinating its conservation.
"In my discussions with our Indonesian navy partners, they share our sense of obligation to protect this and other gravesites," Adm Harry Harris, commander of the US Pacific Fleet, said in a statement.
The Houston, nicknamed "the Galloping Ghost of the Java Coast", sank during the Battle of Sunda Strait on 28 February 1942. Its commanding officer, Capt Albert Rooks, was posthumously awarded the Medal of Honor, the highest US military decoration, for extraordinary heroism during the battle.
All 1,068 sailors and marines on board were presumed dead after the sinking. But when the war ended in 1945, 291 sailors and marines who survived the sinking and three years in prisoner of war camps were repatriated to the US.
US officials laid a wreath at the site in June to commemorate the loss of the ship, but it was only on Monday that the Navy's History and Heritage Command confirmed the wreck was consistent with the sunken warship.