North Korea fires projectiles into the sea off east coast

North Korean leader Kim Jong Un. The country has fired an unidentified projectile into the sea. Photo / AP

South Korea says North Korea has fired several unidentified projectiles into the sea in what appears to be the latest weapons tests for the country that has been rapidly expanding its nuclear weapons and missile program.

Seoul's Joint Chiefs of Staff said the projectiles were fired from an area from the North's eastern coast and flew about 250 kilometers into the Sea of Japan.

The "unidentified projectiles" were fired at 06:49am, 7.07am and 7.19am local time.

The US military said North Korea fired three short-range ballistic missiles, with two of them failing in flight and the third blowing up "almost immediately."

A spokesman for US Pacific Command said none of the missiles, which it said were launched near Kittaeryong, had posed a threat to either North America or the US Pacific territory of Guam.

"The first and third missiles... failed in flight. The second missile launch... appears to have blown up almost immediately," said the spokesman, Commander Dave Benham, adding that the launches happened over a span of 30 minutes.

The North's move was immediately reported to President Moon Jae-in.

"The military is keeping a tight surveillance over the North to cope with further provocations", the ministry added.

The North tends to test-fire balistic missiles or other projectiles - including those from long-range multiple rocket launchers - in response to US-South Korea joint military exercises.

Tens of thousands of South Korean and US troops are taking part in the "Ulchi Freedom Guardian" joint military drills, a largely computer-simulated exercise that runs for two weeks in the South.

The north's latest provocative moves comes as US President Donald Trump is focused on Category Four Hurricane Harvey, which is expected to bring widespread flooding and damage to Texas.

Earlier this month, North Korea reportedly contemplated launching a missile strike against the US Pacific territory of Guam.

North Korea also successfully flight-tested a pair of intercontinental ballistic missiles in July that analysts say could reach deep into the US mainland when perfected

- AAP and AP