The U.S. State Department has assessed that North Korea could build a new underground nuclear test site to replace its Punggye-ri site if it chose to do so. 

In a 2019 compliance report titled “Adherence to and Compliance with Arms Control, Nonproliferation and Disarmament Agreements and Commitments” published this month, the department says the North's apparent destruction of the site last year is “almost certainly reversible.”

North Korea announced on May 25 last year that the site had been "completely dismantled" after imploding tunnel entrances. Foreign journalists were invited to witness the destruction from afar, but international inspectors were not invited to verify the physical location.

The State Department assessed the dismantlement of the Punggye-ri site and the absence of nuclear tests since as positive signals that Pyongyang has intent to move towards implementation of its commitment to denuclearization.

However, it added that the North's refusal to accept international inspectors to verify the dismantlement of the nuclear test site raises doubts about the North's sincerity.

It also said the U.S. believes there is a clear likelihood of additional unidentified nuclear facilities in North Korea.