The repatriation is part of an agreement Trump signed with North Korean leader Kim Jong-un at their historic summit in Singapore last week. The site is mainly used to test large Paektusan engines built for long-range missiles such as the Hwasong-15. Trump told reporters after the two met that Kim had agreed to destroy one of his missile centers.
The testing site in question is in Ch'olsan County, North Pyongan province, and is sometimes is referred to as the Sohae Satellite Launching Ground, according to an administration official. The following month, North Korea invited foreign journalists to witness the destruction of it's only known nuclear testing site in Punggye-ri.
China and the United States both hope to see the Korean peninsula free of nuclear weapons.
The focus on the missile site coincided with growing impatience from Washington to Seoul for some tangible progress on the denuclearization deal.
There was no official confirmation of the return from the relevant USA authorities. Although unwritten, it was the only specific step agreed upon at the summit for dismantling Pyongyang's nuclear weapons program. The violent scenes of American war crimes or crushing USA troops are starting to give way to signs that push for the success of an ongoing five-year economic growth plan, reports NK News. But it's unclear what Trump meant when he went on to say "it was actually four of their big test sites". "The site will be destroyed very soon".
After a series of key advances in North Korean missile and nuclear technology were matched with a heated war of words between the US and North Korea last year, Kim reached out to USA -backed South Korea for peace talks at the beginning of this year. "The detailed negotiations have not begun", Mattis said.More news: Players still far from clear over workings of VAR, says Kyle Walker
The two-day visit which ends Wednesday is created to reassure Beijing that Pyongyang will not neglect its interests as Trump and the young autocrat move into uncharted diplomatic terrain.
Chinese President Xi Jinping talks with North Korean leader Kim Jong Un during his visit in Beijing, China, in this undated photo released June 20, 2018 by North Korea's Korean Central News Agency.
The North Korean leader also visited a traffic control centre in Beijing before departing for Pyongyang on Wednesday afternoon, KCNA said. At the meet, North Korea confirmed its "unwavering commitment to denuclearisation of the Korean peninsula".
Xi said for a period of time, with joint efforts of parties concerned, the Korean Peninsula issue had been put back on the right track of seeking settlement through dialogue and consultation, and the situation on the Peninsula was developing towards peace and stability.
Meanwhile, the Republican chairman of a key House subcommittee on Asia cast aspersions on the summit agreement and called on Washington to be vigilant that China may seek to delay the denuclearization process.