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.

Due to sanctions against him, Kim Yong Chol is banned from visiting the United States normally. His visit to the United States would indicate a waiver was granted.

The United States and South Korea blacklisted Kim Yong Chol for supporting the North’s nuclear and missile programs in 2010 and 2016, respectively.

Yonhap added Choe Kang Il, a North Korean foreign ministry official involved with North America issues, was also spotted at Beijing Capital International Airport. Yonhap did not say whether Choe would be accompanying Kim Yong Chol.

In a flurry of diplomacy over the weekend, Kim Jong Un and South Korean President Moon Jae-in held a surprise meeting on Saturday at the border village of Panmunjom, during which they agreed the North Korea-U.S. summit must be held.

And on Sunday, the U.S. State Department said American and North Korean officials had met at Panmunjom. Sung Kim, the former U.S. ambassador to South Korea and current ambassador to the Philippines, led that American delegation, an American official told Reuters.

Moon said on Monday that there could be more impromptu talks between the two Koreas in the lead-up to the summit.

In Kim and Moon’s first, upbeat meeting on April 27, they agreed to seek the “complete denuclearisation” of the Korean peninsula – but didn’t define what that meant, or how that would proceed.

Since then, North Korea has rejected U.S. demands for it to unilaterally abandon its nuclear weapons programme that experts say could threaten the United States.

Pyongyang also demanded the United States halt future joint military drills with South Korea if it truly wishes for talks with North Korea, the North’s Rodong Sinmun said on Tuesday. In response to reporters’ questions regarding the report, South Korea’s defense ministry said it does not have plans to change joint exercise schedules with the United States military.

Analysts believe Washington is trying to determine whether North Korea is willing to agree on sufficient steps towards denuclearization to allow a summit to take place.

North Korea defends its nuclear and missile programs as a deterrent against perceived aggression by the United States, which keeps 28,500 troops in South Korea, a legacy of the 1950-53 Korean War, which ended in a truce, not a peace treaty.

It has long said it is open to eventually giving up its nuclear arsenal if the United States withdraws its troops from South Korea and ends its “nuclear umbrella” alliance with Seoul.