A North Korean envoy has arrived in Washington for expected talks with US Secretary of State Mike Pompeo and a possible encounter with US President Donald Trump aimed a laying the groundwork for a second summit.

The envoy arrived on the same day Mr Trump announced a revamped US missile defence strategy that singled out North Korea as an ongoing and "extraordinary threat".

It came seven months after he declared after his first summit with leader Kim Jong-Un that the North Korean threat had been eliminated.

Kim Yong Chol, Pyongyang’s lead negotiator in denuclearisation talks with the USs, is due to meet Mike Pompeo and could also go to the White House today, a person familiar with the plan said.

It is a sign of potential movement in a diplomatic effort that has appeared stalled for months.

The North Korean visit could yield an announcement of plans for another summit between Mr Trump and Kim Jong-Un, the source said, speaking on condition of anonymity.

There has been no indication, however, of any narrowing of differences over US demands that North Korea abandon a nuclear weapons programme that threatens the US or Pyongyang’s demand for a lifting of punishing sanctions.

Kim Yong Chol, a hardline former spy chief, arrived in Washington on a commercial flight from Beijing, South Korea’s Yonhap news agency reported.

Yonhap and other South Korean media said he was greeted at Dulles airport by Stephen Biegun, the US special representative for North Korea.

Mr Pompeo had planned to meet his North Korean counterpart to discuss a second summit last November, but the meeting was postponed at the last moment.

Diplomatic contact was resumed after Kim Jong-Un delivered a New Year speech in which he said he was willing to meet Mr Trump "at any time", South Korea’s ambassador to the United States, Cho Yoon-je, told reporters last week.

Kim Yong Chol was last in Washington in June, when he delivered a letter from Kim Jong-Un to Mr Trump that opened the way for the 12 June summit in Singapore.

That meeting yielded a pledge from the latter to work toward denuclearisation of the Korean peninsula and Mr Trump declared the next day that there was "no longer a nuclear threat from North Korea".

There has been little obvious progress since, however, which was underlined by the Missile Defense Review announced yesterday.

Introducing the report, acting US Defense Secretary Patrick Shanahan noted that North Korean missiles remained a "significant concern".

Mr Trump himself only mentioned North Korea in passing at the same event, saying negotiations he had conducted should have been done years ago.