Satellite images out of North Korea show construction at a nuclear testing facility the country previously claimed it destroyed, according to analysts. 

"We have been monitoring the Punggye-ri nuclear test site closely for signs that North Korea was beginning to repair the site," Jeffrey Lewis, of the James Martin Center for Nonproliferation Studies at Middlebury Institute of International Studies, told NBC News

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"In the image, we see very early signs of activity at the new site, including construction of a new building, repair of another building and what is possibly some lumber and sawdust," he said. "North Korea uses a substantial amount of wood at the site both for buildings and shoring up tunnels. These changes occurred only in the past few days."

North Korea nuclear testing facility

Annotated images of Punggye_ri provided by Middlebury Institute of International Studies James Martin Center for Nonproliferation Studies (Satellite image ©2022 Maxar Technologies)

U.S.-based commercial satellite firm Maxar took the images Friday and were analyzed by Lewis and other analysts at the Martin Center. 

Lewis said the images may indicate North Korea plans to resume nuclear explosives testing at the site, though that would be months or years down the road. Nuclear testing at another location, or not at all, is also in the realm of possibility, NBC reported. 

North Korea nuclear testing facility

Annotated images of Punggye_ri provided by Middlebury Institute of International Studies James Martin Center for Nonproliferation Studies (Satellite image ©2022 Maxar Technologies)

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The images show what are believed to be the first changes at the nuclear testing facility that North Korea flamboyantly claimed to have destroyed in 2018. 

North Korea nuclear testing facility

Annotated images of Punggye_ri provided by Middlebury Institute of International Studies James Martin Center for Nonproliferation Studies (Satellite image ©2022 Maxar Technologies)

The hermit kingdom invited a handful of journalists to the country in May of that year to watch explosions ostensibly destroy the testing site, though the extent of the destruction remained unclear to experts. North Korean dictator Kim Jong Un announced an end to nuclear and missile testing that year amid diplomatic talks with the Trump administration. 

 Mike Pompeo and Kim Jong Un

PYONGYANG, NORTH KOREA - UNDATED: In this handout provided by The White House, CIA director Mike Pompeo (L) shakes hands with North Korean leader Kim Jong Un in this undated image in Pyongyang, North Korea. Pompeo, now confirmed as Secretary of State, spoke with Kim for more than an hour during a secret visit over the Easter weekend.  (Photo by The White House via Getty Images) (Getty Images)

North Korea has tested short-range missiles over the last year, including on Friday when the images were taken, NBC News reported. 

Lewis said that "one aspect of having so many commercial satellites in orbit is that we often catch construction activities in their very early stages, when it is difficult to conclude what precisely is being built or why."

"However, this is the first activity we have seen at the site since North Korea dismantled it in May 2018."

A Department of Defense spokesperson told Fox News Digital on Monday that it does not comment on "matters of intelligence or commercial imagery analysis," but is aware of the threat posed by North Korea. 

"We have been very clear on the threat posed by the Democratic People’s Republic of Korea (DPRK) missile programs, and our commitment to the defense of the ROK, Japan, and the U.S. homeland, and our commitment to uphold regional peace and stability," the DoD spokesperson said.

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North Korea was one of five nations last week to vote against the U.N. resolution condemning Russia’s invasion of Ukraine

Japanese officials condemned North Korea’s missile test over the weekend amid the war between Russia and Ukraine as "unacceptable."

"This launch comes at a time when the international community is dealing with Russia's invasion of Ukraine, and also when the Beijing Paralympics are being held. It is unacceptable," Kishi said, according to the Japan Times.

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"The significant pace that North Korea is developing its missile technology is not something our country and the surrounding regions can overlook," Nobuo Kishi, Japan’s defense minister, said Saturday.