Russia's foreign minister is to visit North Korea to hold talks with his counterpart about the situation on the Korean peninsula, the Kremlin says.
Sergei Lavrov's visit on Thursday comes ahead of a planned summit between Donald Trump and Kim Jong-un on North Korean denuclearisation next month.
The foreign ministry said in a statement Wednesday that Mr Lavrov would hold talks with North Korea's foreign policy chief to discuss bilateral issues as well as the overall issues surrounding the Korean Peninsula.
The move comes amid expected talks this week between a top North Korea official and US secretary of state Mike Pompeo.
Mr Trump tweeted on Tuesday he had a "great team" working on the summit and confirmed that Kim Yong-chol, vice chairman of the North Korean ruling party's central committee, was headed to New York.
Teams of US officials have also arrived at the Korean demilitarized zone and in Singapore to prepare for the meeting, initially scheduled for 12 June.
The on-again, off-again drama has been cast by US officials as in keeping with Mr Trump's deal-making style, and reflective of the two leaders testing each other.
After the North's combative statements, there was debate inside the Trump administration about whether it marked a real turn to belligerence or a feint to see how far Mr Kim could push the US in the lead-up to the talks.
Mr Trump had mused that Mr Kim's "attitude" had changed after the North Korean's surprise visit to China two weeks ago, suggesting China was pushing Mr Kim away from the table.
Mr Trump's letter last week, in which he initially cancelled the meeting, was designed to pressure the North on the international stage for appearing to have cold feet, aides said.
White House officials maintain that Mr Trump was hopeful the North was merely negotiating, but that he was prepared for the letter to mark the end of the two-month flirtation.
Instead, the officials said, it brought both sides to the table with increasing seriousness, as they work through myriad logistical and policy decisions to keep 12 June a viable option for the summit.
The flurry of diplomatic activity intensified with Kim Yong Chol's appearance at a Beijing airport on Wednesday. South Korea-based Yonhap News cited diplomatic sources as saying the official was on an Air China flight that departed in the afternoon.
He will be the highest-level North Korean official to travel to the United States since 2000, when late National Defense Commission first vice chairman Jo Myong-rok visited Washington, South Korea's Unification Ministry said.
Mr Pompeo has travelled to Pyongyang, North Korea's capital, twice in recent weeks for meetings with Kim Jong-un, and has said there is a "shared understanding" between the two sides about what they hope to achieve.
Meanwhile, a team of American diplomats is holding preparatory discussions with North Korean officials at the DMZ. The group first met with its counterparts on Sunday, and was seen leaving a Seoul hotel on Tuesday, but it was unclear whether they went to Panmunjom, a village that straddles the border inside the DMZ.
The US officials are led by Sung Kim, the US ambassador to the Philippines, who was formerly the US ambassador to Seoul and a top negotiator with North Korea in past nuclear talks. It includes senior officials with the National Security Council and the Pentagon.
The White House emphasised that it has remained in close contact with South Korean and Japanese officials as preparations for the talks continue.
White House press secretary Sarah Huckabee Sanders said Mr Trump will host Japanese prime minister Shinzo Abe of Japan on 7 June to coordinate their thinking ahead of the summit. Mr Trump hosted South Korean president Moon Jae-in last week.
Mr Moon, who has lobbied hard for nuclear negotiations between Mr Trump and Kim Jong-un, held a surprise meeting with the North Korean leader Saturday in an effort to keep the summit alive.
South Korean media also reported that a North Korean delegation arrived in Singapore on Monday night, where other US officials, led by White House deputy chief of staff Joe Hagin, are preparing for the summit.
Additional reporting by AP.
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