North Korea has reportedly drawn up a new war plan focusing on repelling a possible U.S. attack and on underground protection facilities.

The plan, which was issued nationwide last year, urges the Stalinist state to be prepared to fully mobilize within 24 hours of war breaking out.

The plan places high priority on "a defense strategy" rather than the North's previous offense-oriented war scenarios.

The plan was worked out by the National Defense Commission, led by leader Kim Jong-Il, and urges North Koreans to conduct a three-phase war - defense, offense and then protracted warfare.

It requires all government offices and military units to set up command posts at underground tunnels across the nation in case of military conflict.

A government official in Seoul said the new war plan should not viewed as a military strategy but simply as a guideline for North Koreans on how to respond in case of a possible wartime emergency.