* Senior N.Korea official headed to United States - Yonhap
* N.Korean leader's de facto chief of staff in Singapore - NHK
* US 'pre-advance team' also head to Singapore - White House
* Another US team met N.Koreans in fortified DMZ
North Korea has dispatched top officials to the United States and Singapore, media reported on Tuesday, the latest indication that the on-again-off-again summit with US President Donald Trump may go ahead.
North Korea's Kim Yong Chol, vice chairman of the ruling Workers' Party's Central Committee, 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.
North Korean leader Kim Jong Un's de facto chief of staff, Kim Chang Son, meanwhile, flew to Singapore via Beijing on Monday night, Japanese public broadcaster NHK reported.
At the same time, a "pre-advance" team was travelling to Singapore to meet with North Koreans, the White House said.
US government officials, including the White House deputy chief of staff for operations Joe Hagin, left US Yokota Air Base in Japan for Singapore on Monday, NHK said.
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.
Choe Kang Il, a North Korean foreign ministry official involved with North America issues, was also spotted at Beijing Capital International Airport, according to Yonhap. It did not say whether Choe would be accompanying Kim Yong Chol.
If his trip is confirmed, Kim Yong Chol would be the most senior North Korean official to meet with top officials in the United States since Jo Myong Rok, a marshal, met with then-President Bill Clinton at the White House in 2000.
A former military spy chief, Kim Yong Chol has been a central player in the recent thaw in relations between North Korea and South Korea, as well as the United States.
Kim joined Kim Jong Un in both of his two meetings with South Korean President Moon Jae-in in April and May, and hosted US Secretary of State Mike Pompeo when his visited Pyongyang most recently early this month.
The United States and South Korea blacklisted Kim Yong Chol for supporting the North's nuclear and missile programmes in 2010 and 2016, respectively.
Due to sanctions against him, Kim Yong Chol is banned from visiting the United States normally. Any visit to the United States would indicate a waiver was granted.
During his tenure as a senior intelligence official, Kim was accused by South Korea of masterminding deadly attacks on a South Korean navy ship and an island in 2010, and was linked by US intelligence to a cyberattack on Sony Pictures in 2014. North Korea denied any involvement in the attack on the ship and on Sony Pictures.
In a flurry of diplomacy over the weekend, Kim Jong Un and South Korea's Moon held a surprise meeting on Saturday at the border village of Panmunjom, during which they agreed the North Korea-US summit must be held.
And on Sunday, the US State Department said American and North Korean officials had met at Panmunjom. Sung Kim, the former US ambassador to South Korea and current ambassador to the Philippines, led that American delegation, an American official told Reuters.
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 US 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 denuclearisation to allow a summit to take place.
North Korea defends its nuclear and missile programmes 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.