The Japanese government has decided to proceed with the United States in developing a joint missile defense shield, a top government official said Saturday. Chief Cabinet Secretary Shinzo Abe said steps would be taken to ensure the decision to pursue the shield, which uses defensive missiles to destroy attacking ones before they reach their targets, does not violate Japan's pacifist constitution. "Amid proliferation of the weapons of mass destruction and ballistic missiles, the system is a genuinely defensive, and the only instrument to protect the lives and assets of our people," Abe said. "It suits the defense policy of our country, whose policy is to limit forces for defense." However, the project calls for Japan to relax its arms export laws to deploy the system - a major shift from the 1967 policy that bans weapons shipments to communist bloc nations, countries under UN arms embargoes or those engaged in conflicts.