N KOREA TEST-FIRES SUBMARINE MISSILE

North Korea test-fired a submarine-launched missile 500 kilometres towards Japan, marking what weapons analysts called a clear step forward for its nuclear strike ambitions.

The flight distance, which was tracked by South Korea's military Joint Chiefs of Staff, far exceeded any previous SLBM tests, suggesting significant progress in technical prowess.

A proven SLBM system would take North Korea's nuclear strike threat to a new level, allowing deployment far beyond the Korean peninsula and a "secondstrike" capability in the event of an attack on its military bases.

"While there are still a lot of questions about the details, this test certainly seems to have been successful," said Jeffrey Lewis, director of the East Asia Nonproliferation Program at the Middlebury Institute of International Studies in California.

"This system is still in development, but North Korea is clearly making progress," Lewis told AFP.

South Korea's Yonhap news agency cited a military source as saying Wednesday's launch had been made at an acute angle to limit the missile's range. If fired at the optimum angle, it could cover more than 1,000km, the source said.