Sanctions on North Korea to continue: White House

Trump imposed the "heaviest-ever" sanctions on North Korea's shipping companies last month in a bid to prevent the reclusive nation from acquiring nuclear weapons and developing intercontinental ballistic missiles.

The administration believes the sanctions must remain as it "is really what differentiates, the President's policy from the policies of the past," the official told reporters yesterday.

"If we look at the history of these negotiations that took place under prior administrations, the relinquishing of pressure have often lead to concessions being made to North Korea in return for talks," the official said on the condition of anonymity.

The official said that Trump had been very clear from the beginning that he was not prepared to reward North Korea in exchange for talks.

"But he is willing to accept an invitation at this time to meet and really expects North Korea to start putting action to the words that were conveyed via the South Koreans,” the official said.

The official, however, said there was no letter from Kim regarding the timing of the meeting of the two leaders.

"There was not a letter. This was a message conveyed orally by Kim Jong-un to the National Security Adviser of the South Korea during the several hours of meetings that they held a couple days ago in Pyongyang. Ambassador Chung, who is the National Security Adviser then conveyed it orally to the president today in the Oval Office," the official said.

Details of the place and timing of the meeting are yet to be worked out, the official said.

Ever since he came into office, Trump has emphasised that the urgent matter of denuclearising North Korea was something that required a new approach, the official said.

"It would require us avoiding the mistakes that have been made over the past 27 years of dialogue, and failed approaches to denuclearise North Korea,” another senior administration official said.

Within the matter of weeks, the Trump administration had developed a policy that the president signed to maximise pressure on North Korea.

That meant maximising economic pressure, isolating North Korea diplomatically and marshaling not only our resources, not only the resources of our allies and friends, but rally of the entire world to resolve something that is destabilising to the region and rally to the world at large, the official said on condition of anonymity.

"And so in the year that he pursued that policy, he has always left the door open to dialogue at the right time" the official said.

Yesterday Trump was briefed by South Korean National Security Adviser Chung Lee Young and South Korean intelligence director at the Oval Office.

US National Security Adviser Lt Gen H R McMaster, Defence Secretary James Mattis and White House Chief of Staff John Kelly, Director of National Intelligence Dan Coats along with officials from the CIA were also present in the meeting.

The South Korean delegation gave a readout of their meetings with the North Korean leader Kim Jong-un. They also conveyed a message from Kim to the president.

"Part of that message was a commitment to denuclearised. It also was a commitment to refrain from testing nuclear weapons or missiles. And it was also an invitation (for Trump). Kim Jong-un also made clear that he understands that a routine defencive exercise between the Republic of Korea and the United States will continue,” the official said.

"He conveyed that he wants to meet with President Trump as quickly as possible. President Trump has agreed to accept the invitation to meet with Kim in a matter of a couple of months. The exact timing and place is still to be determined," the official said.

"Obviously verification would go hand in hand with any kind of acceptable deal to put for permanent denuclearisation of North Korea. We will settle for nothing less than that outcome. It is the outcome that the entire world expects it as exemplified under all of those UN Security Council resolutions,” he said.

Trump also briefed Japanese Prime Minister Shinzo Abe on the developments, the official said.