THE United States of America’s media have reported that a North Korean submarine is missing and presumed sunk.
The vessel was operating off the North Korean coast for several days when it disappeared, a paper with close links to the US military says.
The accident comes at a time of heightened tension in the region as South Korea and the US continue their largest-ever military exercise.
North Korean has issued another threat of war over the drill.
It said it was prepared to launch a pre-emptive strike in response to any sign that an invasion was being prepared.
According to the US Naval Institute journal, officials said the US Navy was tracking the submarine when it suddenly disappeared.
It says the North Korean military operates a fleet of about 70 submarines ranging in sizes.
The US military had observed the North Korean navy searching for the missing submarine, CNN reports.
BBC Korea reported that North Korea has two submarine bases on the eastern coast, facing Japan, and the submarine was thought to have been operating near these bases.
If the North Korean submarine has sunk, it is not known if its difficulties were connected to the current stand-off between North and South, our reporter says.
Security tensions have increased since the North tested a nuclear device in January.