Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

North Korea's Sohae long-range rocket site is now back to "normal operating status," according to new commercial images and analysis from two teams of researchers, a reversal of action Kim Jong Un had taken after the first summit with President Donald Trump.

"These actions amount to a 'snapback' from the moderate dismantlement undertaken by the North Koreans at the Sohae launch facility after the Singapore Summit in June 2018," according to an analysis by Joseph Bermudez and Victor Cha of Beyond Parallel, a research project funded by the think tank Center for Strategic and International Studies (CSIS).

The images taken on March 6 show activity that "speaks to the ease with which [North Korea] can reverse steps it might take toward denuclearization in the future," Bermudez and Cha wrote.

A team of researchers from 38 North, which is affiliated with The Stimson Center in Washington D.C., arrived at the same conclusion that the Sohae facility "appears to have returned to normal operational status."

Commercial satellite imagery acquired on March 6, 2019 shows that North Korea has continued the rebuilding of key components at the Sohae Launch Facility, including the vertical engine test stand. CSIS

The new analyses come two days after Beyond Parallel provided commercial imagery to NBC News that it said showed North Korea is pursuing the "rapid rebuilding" of the Sohae Launch Facility.

The activity was photographed on March 2, according to the researchers, less than 48 hours after the Trump-Kim summit in Vietnam broke down.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

The White House did not immediately return a request for comment on the new images. White House Press Secretary Sarah Sanders declined comment when asked on Tuesday about the earlier batch of photos, saying "we don't comment on intelligence."

On Wednesday, Trump said he would be "very disappointed" if North Korea is rebuilding the Sohae facility but emphasized that the "relationship is good."

The president has repeatedly used the fact that North Korea has not launched a missile since late 2017 as a sign that the diplomatic process is working.

After Trump and Kim held talks in Singapore last June, Trump said North Korea agreed to destroy a missile engine testing site, even though that was not part of the final summit declaration.

Speaking at a press conference after the summit, Trump said: "They secured the commitment to destroy the missile engine testing site. That was not in your agreement. I got that after we signed the agreement. I said, 'Do me a favor. You've got this missile engine testing site. We know where it is because of the heat." It's incredible the equipment we have, to be honest with you. I said, 'Can you close it up?' He's going to close it up."

Several weeks after the summit, North Korea dismantled some parts of the Sohae launch site, but, according to both Beyond Parallel and 38 North, the dismantlement has been reversed.

The new imagery shows the North Koreans have reassembled the vertical engine test stand, rail transfer structure, and fuel/oxidizer bunker roofs, Bermudez and Cha wrote.

"The rebuilding activities at Sohae demonstrate how quickly North Korea can easily render reversible any steps taken towards scrapping its [weapons of mass destruction] program with little hesitation. This poses challenges for the U.S. goal of final, irreversible and verifiable denuclearization," according to the researchers.

The vertical engine test stand "has been rebuilt," and there is evidence of construction of a new environmental shelter on the entrance ramp, which "could indicate deliberate preparations to test rocket engines again."

The rail-mounted transfer structure has also been rebuilt, and "moved back to its normal location." This structure is used to move rockets to and from the processing tower.

While there is no evidence of a missile at the site, Bermudez and Cha noted that "the environmental shelters on the umbilical tower, which were opened four days ago to show the launch pad and no rocket is present, have been closed."

In their analysis, the researchers at 38 North said the images show that "construction to rebuild the launch pad and engine test stand that began before the Hanoi Summit has continued at a rapid pace."