Indonesia’s Navy on Saturday declared its missing submarine had sunk and cracked open, killing 53 crew members aboard, after finding items from the vessel over the past two days.

Military chief Hadi Tjahjanto said the presence of an oil slick as well as debris near the site where the submarine’s last dive on Wednesday off the island of Bali were clear proof the KRI Nanggala 402 sank. Indonesia earlier considered the vessel to be only missing.

Navy Chief Yudo Margono told a press conference in Bali, “If it’s an explosion, it will be in pieces. The cracks happened gradually in some parts when it went down from 300 m to 400 m to 500 m... If there was an explosion, it would be heard by the sonar.”

The Navy previously said it believes the submarine sank to a depth of 600-700 m, much deeper than its collapse depth of 200 m, at which point water pressure would be greater than the hull could withstand.

The cause of the disappearance was still uncertain.

Findings to be evaluated

Adm. Margono said searchers found parts of a torpedo straightener, a grease bottle believed to be used to oil the periscope, debris from prayer rugs and a broken piece from a coolant pipe that was refitted on the submarine in 2012.

“With the authentic evidence we found believed to be from the submarine, we have now moved from the ‘sub miss’ phase to ‘sub sunk,’” Adm. Margono said.

He said rescue teams from Indonesia and other countries will evaluate the findings. He said no bodies have been found so far. Officials previously said the submarine’s oxygen supply would have run out early on Saturday.

An American reconnaissance plane, a P-8 Poseidon, landed on Saturday and had been set to join the search, along with 20 Indonesian ships, a sonar-equipped Australian warship and four Indonesian aircraft.

Singaporean rescue ships were also expected on Saturday, while Malaysian rescue vessels were due to arrive on Sunday, bolstering the underwater hunt, officials said earlier Saturday.

The German-built KRI Nanggala 402 has been in service in Indonesia since 1981 and was carrying 49 crew members, three gunners and its commander, the Defence Ministry said.