And with its work at the Sohae site, Pyongyang may be the first to take such steps after images taken Wednesday showed that a rail-mounted structure to transfer rockets to the launchpad there appeared to have been completed and "may now be operational", the North Korea-watching website 38 North said, citing commercial satellite imagery used to track construction that they said began before the Hanoi summit.
The official, who requested anonymity, recalled the President's statement that he would be "very, very disappointed" if reports of activity at the site were true.
Kim reportedly pledged to dismantle Sohae during his meeting with Trump in Singapore.
According to senior United States officials, in the week leading up to the Hanoi summit, the North Koreans had demanded the lifting of effectively all UN Security Council economic sanctions imposed on Pyongyang since March 2016.
"The intent of the North Koreans in this matter is known only to them".
It also came amid reports that there are signs of North Korea restoring part of the Dongchang-ri missile launch site that it began to dismantle previous year. Inside South Korea, opinions favoring Moon taking a leading role in worldwide engagement with the North are mixed up with a desire for greater cooperation with the U.S.
South Korea's presidential office and defense ministry declined to confirm the Sanumdong reports and the U.S. State Department said it could not comment on intelligence matters.
US National Security Adviser John Bolton and other USA officials have sought to play down the developments spotted at Sohae, although Trump on March 7 called recent North Korean activity "disappointing". "As the president said, it would be very, very disappointing if they were taking this direction".
But Kim's appointment could also exacerbate divisions within Moon's government, some analysts said, and fuel US concerns that the South may be moving too quickly with the North.
Satellite images of a North Korean rocket assembly facility suggest possible launch preparations, Jeffrey Lewis, director of the East Asia Nonproliferation Project at the Middlebury Institute of International Studies at Monterey, told CNN on Friday.
North Korean leader Kim Jong-un has picked economic development as his country's urgent task, state media said Saturday, amid speculation that the North may launch a rocket.
"We have to assume they are going to have to cheat, assume they keep their nuclear weapons, no matter what", King continued, adding it is important for the United States to keep its sanctions on and keep some of its military activity active in South Korea.
Palladino would not say if Washington had been in contact with Pyongyang over Sohae, situated on North Korea's northwest coast, or the aborted summit. But the meeting broke down over an impasse regarding how many sites North Korea would shut down.
President Moon Jae-in has replaced his unification minister who played a major role in last year's detente with the Democratic People's Republic of Korea (DPRK), his office said on Friday, and named a longtime confidant to lead Moon's drive for "a new Korean peninsula".