U.S. Secretary of State Mike Pompeo met with North Korean officials in a second day of talks on the country's nuclear program.

U.S. Secretary of State Mike Pompeo began a second day of talks in North Korea on Saturday in Pyongyang about the North’s nuclear weapons program.

U.S. Secretary of State sat down again with Kim Yong Chol, a top North Korean party official and former spy agency chief who played a key role with Pompeo in arranging the June 12 summit between U.S. President Donald Trump and North Korean leader Kim Jong Un in Singapore.

Kim Yong Chol said that the two had had “very serious discussion on very important matters yesterday” and joked that as a result, Pompeo “might have not slept well last night".

Pompeo replied: “We did have a good set of conversations yesterday. I appreciate that and I look forward to our continued conversations today as well.”

Kim agreed that the work was important. “There are things that I have to clarify. There are things that I have to clarify as well,” U.S. Secretary of State said.

Meanwhile, U.S. State Department spokeswoman Heather Nauert told reporters that U.S. and North Korean officials had set up working groups to deal with “nitty gritty stuff,” including verification of efforts to achieve denuclearization, which would be headed on the U.S. side by Sung Kim, a Korean-American who is also ambassador to the Philippines.

Nauert said Pompeo’s discussions with North Korean officials also included repatriation of American Korean War remains.

It is Pompeo’s third visit this year to North Korea and the first where he stayed overnight. It is also his first visit since Trump met with Kim at last month’s Singapore summit.

The much-anticipated Trump-Kim Jung-Un summit has finally taken place in Singapore last month.

Donald Trump decided to walk away from a multi-lateral nuclear agreement signed by his predecessor, Barack Obama, thereby dishonoring and reneging on America's international commitments and obligations.