US PRESIDENT Donald Trump and South Korean President Moon Jae-in, who are both planning to meet North Korea’s leader Kim Jong-un in the next two months, have pledged to maintain “maximum pressure” on his authoritarian regime and seek action on giving up his nukes, the White House said.

In a phone call with Mr Moon, Mr Trump reiterated his intention to meet Mr Kim by the end of May.

According to a White House statement, the allied leaders “agreed that concrete actions, not words, will be the key to achieving permanent denuclearisation of the Korean Peninsula.” They also agreed that a “brighter future is available for North Korea, if it chooses the right path,” the White House stated.

Mr Moon is due to meet Mr Kim in April, a prelude to what would be the first US-North Korean summit in seven decades of hostility since the 1950-53 Korean War.

Preparations for the Trump-Kim summit, which was announced out of the blue last week, were always going to be tricky.

Now, they have been thrown an early curve ball with Secretary of State Rex Tillerson’s abrupt firing by Mr Trump last Tuesday.

North Korea has yet to publicly confirm the summit plans, and the venue for the meeting remains up in the air, although a rare visit by the North’s top diplomat to Sweden on Friday fuelled speculation that the Scandinavian nation might even play host.

On Friday, the US official left in charge of the State Department after Mr Tillerson’s departure faced a delicate diplomatic task: to keep America’s key Asian allies on the same page over the outreach to Mr Kim.

Deputy Secretary John Sullivan was meeting separately with Foreign Minister Kang Kyung-wha of South Korea, the nation which teed up the Trump-Kim summit, and Foreign Minister Taro Kono of Japan, whose nation is less enthusiastic and more sceptical about the sudden spirit of rapprochement.

Both nations host tens of thousands of US forces and face a direct threat from North Korea’s weaponry. But South Korea and Japan also have tetchy relations and different perspectives on the problem.

Mr Moon is a longstanding advocate of engagement with the North. He used the Winter Olympics his nation hosted last month to reach out to Pyongyang. Subsequently, South Korean officials met Mr Kim last week and relayed to Washington that the North Korean dictator was committed to “denuclearisation” and willing to halt nuclear and missile tests, which tempted Mr Trump to agree to talk.

Ms Kang followed up on Thursday with a lunch with Ivanka Trump, the president’s daughter and adviser. They also had met during the Olympics closing ceremony.

Japanese Prime Minister Shinzo Abe now appears the odd one out. He’s forged close ties with Mr Trump and been a staunch supporter of his campaign of “maximum pressure” on North Korea, primarily through economic sanctions.

While he says he welcomes the dialogue with North Korea he’s adamant the pariah nation must take real steps toward giving up its nukes.

James Schoff, a former Pentagon adviser on East Asia, said that Japanese officials are unnerved by Mr Trump’s unpredictability and fear that the US could reach a deal with Mr Kim on long-range North Korean missiles that threaten the US without addressing the shorter-range weapons that threaten Japan.

Although Mr Schoff said there’s no reason to think that such a divisive move is in the cards, the Japanese want to be informed and consulted on the summit plans.

“They want to keep up maximum pressure and make sure we don’t cut their interests out in any deal,” he said.