Their talks will be aimed at determining whether a meeting between Trump and Kim Jong-un, originally scheduled for June 12 but later cancelled by Trump, can be restored, US officials have said.
A hotel employee hails a cab at the Shangri-La Hotel in Singapore.
"Come to Russia, we'll be very happy to see you", Lavrov told Kim in remarks released by the Russian foreign ministry.
North Korea defends its nuclear and missile programs as a deterrent against what it sees as United States ambitions to overthrow its leadership and unite the Korean Peninsula.
Pompeo tweeted that he had had a "good working dinner" with Kim on Wednesday night of steak, corn and cheese.
Moscow's top diplomat expressed Russia's support for the declaration between North and South Korea last month, in which they agreed to work for the denuclearisation of the peninsula. To do so, they said they would seek to hold three-way talks among the two Koreas and the United States, or four-way talks involving China.
But the flurry of diplomatic backslapping and bonhomie disappeared in recent weeks with increasingly bellicose rhetoric from both top USA administration officials and Pyongyang. The important thing to dismantling the sprawling atomic complicated, begun six many years in the past, Dr. Hecker added, "is to ascertain a unique relationship with North Korea the place its safety rests on one thing apart from nuclear weapons".
U.S. Secretary of State Mike Pompeo and high-ranking North Korean official Kim Yong Chol entered a second day of meetings in NY on Thursday as they tried to settle nuclear weapons disagreements and set the stage for an historic summit between their leaders.
U.S. officials have also met North Korean envoys in Panmunjom on the inter-Korean border, while more USA diplomats have arrived in Singapore to prepare for the event. Because he has been sanctioned by the US Treasury Department twice, he was given a sanctions waiver to make this trip, The Guardian reported.
"We're moving forward, and we'll be prepared either way".
Top North Korean official arrives in New York for talks on summit
Former North Korean spy chief Kim Yong Chol arrived in New York Wednesday for a meeting with Secretary of State Mike Pompeo . Russian Federation on Wednesday also announced that its foreign minister would be in North Korea on Thursday for talks.
Cheong Wa Dae confirmed Wednesday it had sent an official to Singapore to prepare for Moon's official visit to the city state in July, but it triggered speculation that Seoul may be preparing for a three-way summit between the two Koreas and the US.
North Korean envoy Kim Yong Chol (C), departs from a meeting with U.S. Secretary of State Mike Pompeo in NY, U.S., May 30, 2018.
Thursday also saw Lavrov and Ri discuss trilateral economic cooperation, Lavrov said.
Unlike last month's summit, which was held in front of live TV cameras, Saturday's meeting took place in utmost secrecy, with reporters only told later that it had taken place.
So rather than the technological issues of nuclear disarmament, the main factor could be North Korea's will and sincerity.
"Separately, Joseph Hagin, the White House deputy chief of staff for operations, and the USA pre-advance team, including members from the State Department, are in Singapore this week, where they're conducting logistics of the expected summit", spokesperson Nauert added.
A USA official said negotiations about the summit's agenda have so far been slow going, and the two fundamental issues, the definition of North Korean denuclearization and whether both sides would take actions at the same time or separately, remained unsettled.
Kim was known as a leading student activist in the 1980s who spread North Korea's Juche ideology, but later became an activist promoting democracy and human rights in North Korea.
China on Thursday signaled its intention to actively engage in the process of ending the war. China appears to be struggling to retain influence over issues concerning the Korean Peninsula - key leverage over the US. He didn't take any other questions.
The US, for its part, wants North Korea to remain committed to its pledge on full-fledged de-nuclearization, according to the sources. "Doing so will likely be a political burden for Trump". We will see what happens.
The leading diplomat spoke about the importance of trust in Asia and what a difference between peace and war he thinks it could make, urging the United States to build a relationship based on trust rather than power plays.