North Korea's submarine missile launch 'unforgivable': Abe

Denouncing North Korea's missile launch from a submarine on Wednesday morning, Japan's Prime Minister Shinzo Abe called the move an "unforgivable" threat to regional stability.

US Strategic Command earlier today said the missile, believed to be a KN-11 was fired from the North Korean coastal city of Sinpo at around 5:30 am local time, which flew about 500 km before landing in the Sea of Japan.

"This poses a grave threat to Japan's security, and is an unforgivable act that damages regional peace and stability markedly," the Guardian quoted Abe as saying.

Noting that it was the first time a North Korean missile launched from a submarine had entered Japan's air defence identification zone, Abe said that Japan had lodged a protest with North Korea.

Meanwhile, the officials in Washington said they are ready to defend South Korea and Japan from any provocation.

The move comes a day after North Korea threatened to launch nuclear strikes to protest the start of annual joint U.S.-South Korean military exercises.

According to defence experts, Wednesday's missile launch recorded at 500 km distance is greater than that achieved by previous submarine-launched ballistic missiles [SLBM].

Earlier this year, the country fired two missiles from submarines, but defence officials in Seoul believe they exploded in midair after flying fewer than 30 km.

Meanwhile, as the foreign ministers of Japan, South Korea and China will hold talks in Tokyo today, it is expected that they condemn the missile test.