North Korea has denounced the joint U.S.-Japanese response plan for contingencies involving conflict on the Korean Peninsula.

Under “Operation Plan 5055,” Japan will open its ports, military bases and other facilities to assist the U.S. in the event of a war on the peninsula.

The North’s state-run Korean Central News Agency said Saturday that the drafting of the joint operation plan indicates that the U.S. and Japan are stepping up preparations for a preemptive attack on North Korea.

The KCNA said that the aim of the joint operation plan was to isolate the North through a blockade, speeding up war preparations against the communist country under the cover of talks seeking a peaceful resolution to the nuclear issue.

The news agency warned Japan of disastrous consequences for going along with Washington's hostile policy against Pyongyang.

It went on to say that the North’s self-reliant deterrent forces would bolster readiness in every way to cope with what it called the war moves of the U.S. and Japanese reactionaries.

Japan’s Asahi Shimbun daily Thursday reported that the U.S. and Japan have begun drafting a joint operations plan to respond to possible contingencies on the Korean Peninsula.