North Korea leader says missile test was "greatest success": Media

The missile flew 500 kilometres towards Japan, marking what analysts called a clear step forward for country's nuclear strike ambitions

North Korean leader Kim Jong-Un has declared a recent submarine-launched ballistic missile (SLBM) test the "greatest success", Pyongyang's state media said.

The results of Wednesday's launch proved the North had joined the "front rank of the military powers fully equipped with nuclear attack capability" and that the US mainland and the operational theatre in the Pacific were now "within the striking range" of the North's army, KCNA news agency reported on Thursday Kim as saying.

The missile flew 500 kilometres (around 300 miles) towards Japan, marking what weapons analysts called a clear step forward for North Korea's nuclear strike ambitions.

Kim saw the launch first hand, KCNA reported, although it was not clear where his alleged observation post was.

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 "second-strike" capability in the event of an attack on its military bases.

Kim stressed the need for stepped-up efforts to mount nuclear warheads on all types of ballistic missiles and to develop the means to deliver them in order "to cope with the unpredicted total war and nuclear war with the US imperialists", KCNA said.

"I do not guess what ridiculous remarks the US and its followers will make about this test-fire, but I can say their rash acts will only precipitate their self-destruction," Kim was quoted as saying by KCNA.

Kim issued the order for the test-fire, with the submarine rising to a depth suitable for firing and before launching the ballistic missile, the news agency said.

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.

South Korea's Yonhap news agency cited a military source as saying yesterday's launch had been made at an acute angle to limit the missile's range.

If fired at the optimum angle and fully fuelled, it could over 2,500km, the source said.

The agency previously quoted a military source saying if fired atthe optimum angle it could cover more than 1,000km -- without mentioning if it was fully fuelled.

The test-launch proved that "the core technical indexes of the ballistic missile" met "all requirements for operation", KCNA said.

Kim added that the "US vicious nuclear threat and blackmail against the DPRK (North Korea) only resulted in bolstering up its nuclear attack capability hour by hour", according to KCNA.