North Korea has test-fired a missile into Japanese waters, the latest in a series of launches that have ratcheted up tensions over its nuclear weapons program.

It was North Korea’s third ballistic missile test in as many weeks and the 12th this year – carried out in fresh defiance of UN sanctions warnings and US threats of possible military action.

US military monitors said the short-range missile flew for six minutes, while Japan said it fell into the country’s exclusive economic zone (EEZ) – waters extending 370km from its coast.

The launch comes despite tough talk from US President Donald Trump, who promised last week at the G7 summit that the “big problem” of North Korea “will be solved”.

Monday’s test, a short-range Scud, marks the second time this year that a North Korean missile fell provocatively close to its neighbour Japan.

It flew about 450 kilometres before landing in the Sea of Japan (East Sea) between the Korean peninsula and Japan, the US Pacific Command said.

North Korea has been stepping up efforts towards its ultimate goal – developing an intercontinental ballistic missile that can deliver a nuclear warhead to the continental US.

The isolated but nuclear-armed North Korea has test-fired a missile almost every week for the past three weeks.

Michael Penn, president of the Tokyo-based Shingetsu news agency, said the latest test was part of a North Korean effort to strengthen its military against any possible threats from the US.