John Kerry has called on North Korea’s leaders to “come to the table in a responsible way” to end regional tensions.

Speaking in Tokyo, the fourth and final stop on his Asian tour, US Secretary of State John Kerry warned North Korea it risked further isolation if its threats continued.

John Kerry also reaffirmed the US commitment to defend its allies, including Japan.

The countries the US official had visited were united in seeking the denuclearization of the Korean peninsula.

On Friday John Kerry visited South Korea, and on Saturday he was in China, whose leaders he has said are “very serious” in their pledge to help reduce tensions – and to help end the North Korean nuclear programme.

North Korea has recently threatened attacks against South Korea and the US, sparking alarm in the region.

Speaking in Tokyo, the fourth and final stop on his Asian tour, US Secretary of State John Kerry warned North Korea it risked further isolation if its threats continued

Speculation has been building that the North is preparing a missile launch, following reports that it has moved at least two Musudan ballistic missiles to its east coast.

Japan is within range of these rockets and has been taking precautions, including setting up batteries of US-made Patriot anti-missile systems around the capital and sending two warships to the Sea of Japan, with orders to shoot down any missiles fired towards the Japanese islands.

At a joint news conference with Foreign Minister Fumio Kishida, John Kerry said North Korea had to understand by now “that its threats and provocations are only going to isolate it further and impoverish its people even further”.

“The US will do what is necessary to defend our allies against these provocations, but our choice is to negotiate,” he said.

“We would hope that whatever considerations and fears the North has of the US or others in the region they would come to table in responsible way and negotiate that.”

John Kerry stressed that Seoul, Beijing, Tokyo and Washington had “committed to take action together” and to “making that goal of denuclearization a reality”.

Fumio Kishida said their role was to persuade North Korea that its aggressive behavior “will not benefit them in any way whatsoever” and that the international community had to send out this strong message.

Washington and Tokyo have a security alliance dating back to the 1950s, under which Washington is bound to protect Japan if it is attacked.

On Monday, April 15, North Korea will mark the birth of national founder Kim Il-sung. Such occasions are traditionally marked with shows of military strength and it is thought this year the date could be used for a missile launch.

John Kerry has stressed that it would be a “huge mistake” for North Korea to go ahead with a launch, saying it would further isolate the country and that its people are in need of food, not missiles.

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