North Korea has fired a ballistic missile towards the sea, its first missile launch in about a month, South Korea said.

South Korea’s Joint Chiefs of Staff said the launch took place on Sunday but gave no further details such as how far the weapon flew.

Japan’s Defence Ministry also said it detected a possible ballistic missile launch by North Korea. Japan’s Coast Guard, quoting the Defence Ministry, said the suspected missile is believed to have landed in the ocean.

It is the North’s first missile launch since it test-fired its Hwasong-18 solid-fuelled intercontinental ballistic missile, the North’s most advanced weapon, on December 18. The Hwasong-18 is designed to strike the mainland US.

Sunday’s launch came days after North Korea fired a barrage of artillery shells near the tense sea border with South Korea, prompting South Korea to conduct similar firing exercises in the same area.

In recent days, North Korea has also been escalating its warlike rhetoric against its rivals. Earlier this week, leader Kim Jong Un called South Korea “our principal enemy” and threatened to annihilate it if provoked.

Experts say Mr Kim is likely to further raise animosities by test-firing more missiles to try to raise the stakes in the stand-off with his rivals and influence the results of South Korea’s parliamentary elections in April and the US presidential election in November.

They believe he wants to see South Korean liberals pursue rapprochement with North Korea while maintaining a parliamentary majority status, and for former US president Donald Trump to be elected again. They say Mr Kim might think he could win US concessions like sanctions relief if Mr Trump returns to the White House.

In a key ruling party meeting in late December, Mr Kim vowed to expand his nuclear arsenal and launch additional spy satellites to cope with what he called US-led confrontational moves.