North Korea has set up a new war plan that calls for more underground protection facilities to prepare for a possible U.S. attack on the communist country, South Korean intelligence officials said Wednesday. The 33-page military document, signed by North Korean leader Kim Jong Il in April last year and issued nationwide, also urges the country to be ready to fully mobilize troops, civilians and any other possible resources within 24 hours after war breaks out, according to the National Intelligence Service officials. The South Korean spy agency verified the North's wartime guidelines, which were unveiled by South Korea's Kyunghyang Shinmun newspaper earlier that day, saying the new war plan put priority on a defense posture rather than the previous offense-oriented war scenario. It is the first time that details of the North's wartime plan have been made public in South Korea, officials said. Analysts in Seoul say the North's new defensive war plan reflects Pyongyang's security fears in the wake of the U.S.-led war on Iraq. "The North's document indicates that the North Korean leadership is fearful about a possible U.S. strike on the communist nation over the nuclear standoff," said Kim Tae-hyun, a professor at Chung-Ang University in Seoul. "The North's wartime guidelines may be an updated version of its previous plans to cope with changed security situations facing the country, such as the war in Iraq," said an official at the Defense Ministry. The "Detailed Wartime Guidelines" was issued April 7, 2004, when North Korea was claiming that it could be the next target of the U.S.-led war against terrorism after Iraq. North Korea has been locked in a standoff with the United States over its nuclear weapons drive since last 2002. When the U.S.-led war started in Iraq in March 2003, Kim Jong Il vanished from public view for six weeks, sparking speculation he was hiding in a bunker for fear of attacks. With Saddam Hussein ousted, North Korea and Iran are the two remaining members of what U.S. President George W. Bush dubbed the "axis of evil." The document was signed by Kim Jong Il in his capacity as chairman of the Central Military Committee of the ruling Workers' Party, ending speculation over whether Kim has inherited the important post occupied by his father, Kim Il Sung, before his death in 1994. Kim Jong Il is now ruling the reclusive nation in the capacity of the chairman of the National Defense Commission and supreme commander of the People's Army.