Indonesia's navy is searching for a submarine with 53 people on board after it went missing early yesterday at the end of an exercise near Bali.
Help is also being sought from at least two neighboring countries in the hunt for the German-made submarine KRI Nanggala-402.
It was conducting a torpedo drill in the Java Sea about 100 kilometers north of Bali but had failed to make contact later with the results as expected.
Military chief Hadi Tjahjanto confirmed that assistance in the search for the submarine had been requested from Australia and Singapore.
He also said that contact with the submarine had been lost at 4.30 am yesterday.
The 1,395-tonne KRI Nanggala-402 was built in Germany in 1978. And it had undergone a two-year refit in South Korea that was completed in 2012.
The Indonesian navy has in the past operated a fleet of 12 submarines that were purchased from the Soviet Union to patrol the waters of its sprawling archipelago. But now it has a fleet of only five, including two German-built Type 209 submarines and three newer South Korean vessels.
Indonesia has been seeking to upgrade its defense capabilities, but some of its equipment still in service is old, and there have been a number of deadly accidents involving in particular ageing military transport planes in recent years.