North Korean leader Kim Jong Un shakes hands with U.S. Secretary of State Mike Pompeo in this May 9, 2018 photo released on May 10, 2018 by North Korea's Korean Central News Agency (KCNA) in Pyongyang.

A top aide to North Korean leader Kim Jong Un arrived in Singapore on Monday night, Japanese public broadcaster NHK said on Tuesday, the latest indication that the on-again-off-again summit with U.S. President Donald Trump may go ahead.

Kim Chang Son, Kim's de facto chief of staff, flew to Singapore via Beijing on Monday night, the report said.

At the same time, a team of U.S. government officials, including the White House deputy chief of staff for operations Joe Hagin, left U.S. Yokota Air Base in Japan for Singapore on Monday, NHK said.

The White House said a "pre-advance" team was traveling to Singapore to meet with North Koreans.

The reports indicate that planning for the historic summit, initially scheduled for June 12, is moving ahead after Trump called it off last week. A day later, Trump said he had reconsidered, and officials from both countries were meeting to work out details.

When Kim Chang Son was asked by a reporter at the Beijing airport if he was flying to Singapore for talks with the United States, he said he was "going there to play," according to footage from Nippon Television Network.

Meanwhile, North Korea's Kim Yong Chol, a senior official dealing with inter-Korean affairs was scheduled to fly to the United States on Wednesday after speaking to Chinese officials in Beijing, South Korea's Yonhap news agency said citing an unnamed source.