Two North Korean warships sank during a drill in the East Sea last month, killing scores of sailors. The vessels sank in waters near Wonsan a few days apart in mid-October, a South Korean military source said Sunday.
It is not known why the ships sank and how many were killed. South Korean military authorities spotted attempts by the North Korean navy to salvage their hulls.
The two ships will have been a Hainan-class 375-ton submarine chaser and a 100 to 200-ton patrol boat, according to the source.
"The Hainan-class submarine chaser probably sank because it's old. It was built in China in the 1960s and the North bought it in the mid-70s," the source added.