North Korea says it will resume dismantling a plutonium-producing nuclear plant, now the United States has removed it from its terrorism blacklist.
A foreign ministry spokesman said the North would now resume disabling its nuclear facilities and allow international monitors access.
But Japan has criticised as "extremely regrettable" Washington's decision to remove North Korea from its list of state sponsors of terrorism.
Japan opposed the move because it first wanted North Korea to provide more information about Japanese citizens it abducted in the 1970s and 1980s.
Finance Minister Shoichi Nakagawa said "abductions amount to terrorist acts".
North Korea has admitted to kidnapping 13 Japanese civilians, snatched from beaches on the west coast during the 1970s and 80s to train its spies.
Japan believes the figures could be higher and is skeptical about North Korea's claim that all but five are now dead.