North Korea fires missile into Sea of Japan

South Korea's defence ministry said the missile had flown some 60 kilometres (about 40 miles).

"The military is keeping a close watch over North Korea's provocative moves and maintaining a high defence posture", it said.

The US military said it was a KN-15 medium-range ballistic missile which they had determined posed no threat to America.

"US Pacific Command is fully committed to working closely with our Republic of Korea and Japanese allies to maintain security," the military command in the Indo-Asia-Pacific region said.

US Secretary of State Rex Tillerson confirmed Pyongyang had launched "yet another" intermediate range ballistic missile.

"The United States has spoken enough about North Korea. We have no further comment," he said in a statement.

Japan condemned the launch and said it violated UN Security Council resolutions.

"Japan never tolerates North Korea's repeated provocative actions. The government strictly protested and strongly condemned it," Chief Cabinet Secretary Yoshihide Suga said.

The launch will fuel international concerns about the hermit state's weapons programme.

Pyongyang is on a quest to develop a long-range missile capable of hitting the US mainland with a nuclear warhead, and has so far staged five nuclear tests, two of them last year.

The latest launch came after President Donald Trump threatened the US was prepared to go it alone in bringing the North to heel if China did not step in, and ahead of a meeting with his Chinese counterpart Xi Jinping.

North Korea's foreign ministry on Monday assailed Washington for its tough talk and for an ongoing joint military exercise with South Korea and Japan which Pyongyang sees as a dress rehearsal for invasion.

The "reckless actions" are driving the tense situation on the Korean peninsula "to the brink of a war", a ministry spokesman was quoted as saying by the official KCNA news agency.

The idea that the US could deprive Pyongyang of its "nuclear deterrent" through sanctions is "the wildest dream", it said.

Trump and Xi will hold their first face-to-face meeting at the US president's Mar-a-Lago resort in Florida where the growing tensions on the Korean peninsula are expected to be high on the agenda.

The hardened US stance followed recent North Korean missile launches that Pyongyang described as practice for an attack on US bases in Japan.

In February the North simultaneously fired four ballistic missiles off its east coast, three of which fell provocatively close to Japan.

Last August Pyongyang also successfully test-fired a submarine-launched ballistic missile 500 kilometres towards Japan, far exceeding any previous sub-launched tests, in what the North's leader Kim Jong-Un hailed as the "greatest success".

A nuclear-capable SLBM system would take the North's 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 army bases.

Analysts say that while Pyongyang has made faster progress in its SLBM system than originally expected, it is still years away from deployment.

Pyongyang is barred under UN resolutions from carrying out ballistic missile launches or nuclear tests.