TOKYO -- Indonesian authorities believe a submarine that went missing in the early hours of Wednesday has sunk, carrying 53 crew members.
Naval officials on Saturday revealed debris that they said came from the KRI Nanggala 402. The materials would "not be lifted overboard if there is no outside pressure or a crack occurs in the torpedo launcher," Yudo Margono, the Indonesian navy's chief of staff, told reporters.
The submarine vanished in the early hours of Wednesday when it was conducting a torpedo firing exercise. The last detected signal from the ill-fated vessel was from 850 meters deep, beyond its diving limit.
The vessel's status has been deemed "subsunk," military chief Hadi Tjahjanto said, "because shards have been found and the last location of the ship is at a depth of 850 meters."
Margono explained the sub suffered "a rift, not an explosion. If [the submarine] explodes, it's all gone. So because of the crack, when it started to descend at a depth of 300, 400, 500, there were phases of cracking."
To find the vessel, the navy has deployed 15 ships and a total of four aircraft and helicopters, while other Indonesian authorities have sent four vessels. One Australian frigate and an American Poseidon P8 aircraft were also on the scene on Saturday, with another Australian vessel on the way. Ships from Singapore, Malaysia and India were expected to arrive as well.
Indonesian authorities had said the air on board the Nanggala would last for 72 hours, which gave rescuers approximately until dawn on Saturday to find the sub and extract those on board.
Margono did say the 72-hour time limit referred to a case where the submarine experienced a blackout. He suggested oxygen could last for five days should electricity still be alive on board.
"The tracking team said the lights were all still on when [KRI Nanggala] entered the water," the chief of staff said, hinting that the submarine may not have suffered a blackout.
The German-built submarine has been in service since 1981, and underwent a full refit in South Korea that was completed in 2012. The Indonesian Navy said it was "in good condition."
The last communication with the Nanggala was at 4 a.m. on Wednesday.
When the commander of the training task force tried to authorize the firing drill 25 minutes later, communication with the submarine could not be established. The vessel had been due to surface by 5:15 a.m. on Wednesday morning.
The U.S. will "do everything possible to support Indonesia's search and rescue effort," National Security Adviser Jake Sullivan told Foreign Minister Retno Marsudi in a phone call on Friday, according to a U.S. National Security Council spokesperson.
President Joko Widodo on Thursday said in an online address that the crew was the government's top priority and asked the public to "pray for this search and rescue to be carried out."
Additional reporting by Ismi Damayanti in Jakarta.