The U.S. Air Force is sending a number of teams to assist Indonesia in the search for a submarine that has gone missing with 53 sailors, a Pentagon spokesman has reported.

Indonesian President Joko Widodo, in turn, announced that the authorities would do everything in their power to locate the submarine. The navy had previously announced that the crew would still have oxygen available until Saturday.

The US Department of Defense is ‘heartbroken’ about the news about the submarine that disappeared from the radar on Wednesday during an exercise off the coast of the island of Bali. “Our thoughts are with the Indonesian sailors and their families,” said a Pentagon spokesman.

“At the invitation of the Indonesian government, we are sending air forces to assist in the search for the missing submarine.” US Secretary of Defense Lloyd Austin will speak today with his Indonesian counterpart Prabowo Subianto to discuss how the US can help further, the spokesman said.

Leaked oil found where the submarine went diving points to possible damage to the fuel tank and has heightened fears of a deadly submarine disaster

Indonesia is already receiving support from Malaysia and Singapore, which have sent ships. France, Germany, and Australia have also offered assistance. Indonesia has sent a helicopter and six ships to locate the German-built KRI Nanggala-402.