Japan and the US have begun a three-day military exercise in the Sea of Japan adding pressure on North Korea to halt its accelerating ballistic missile programme.

Japan’s navy sent two ships, including one of its four helicopter carriers, the Hyuga, to join the USS Ronald Reagan and USS Carl Vinson, and their eight escort ships yesterday. Japanese F-15s are also taking part in simulated combat with US F-18s.

“It’s the first time we have exercised with two carriers. It’s a major exercise for us,” a Japanese military spokesman said.

The Sea of Japan separates Japan from the Korean Peninsula.

The United States sent the warships to the region after a surge of tension on the Korean Peninsula over fears the North was about to conduct another nuclear test in its bid to develop an intercontinental ballistic missile capable of hitting mainland United States.

Shinzo Abe, the Japanese Prime Minister, has vowed to work with other countries to deter North Korea, which on Monday conducted a short-range ballistic missile test.

The missile reached an altitude of 120km before falling into the Sea of Japan in international waters, but inside Japan’s exclusive economic zone where it has jurisdiction over the exploration and exploitation of maritime resources.

The launch followed two successful tests of medium-to-long-range missiles in as many weeks.

North Korea can already strike anywhere in Japan with missiles, raising concern in Tokyo that it could eventually be threatened by a nuclear strike.

South Korea’s new liberal President, Moon Jae-in, who took office on 10 May, has taken a more conciliatory line than Mr Abe, pledging to engage with his reclusive neighbour.