U.S. researchers say recent satellite imagery shows that North Korea has begun dismantling facilities at its nuclear test site.

An analysis Monday by the 38 North website says commercial imagery taken last week shows that several operational support buildings have been razed and rails for mining carts have apparently been removed.

North Korea says it will dismantle its Punggye-ri test site between May 23 and 25 in the presence of local and international media. The site has been used for each of its six underground nuclear test explosions.

South Korea’s president on Monday welcomed the announcement as the beginning of North Korea’s nuclear disarmament. It comes ahead of a historic U.S.-North Korea summit.

The analysis says no tunnel entrances at the test site appear to have been permanently closed yet.

(AP)