Defense chief vows to bolster cooperation with U.S., Japan against N.K. threats

South Korea's defense chief pledged Wednesday to strengthen trilateral security cooperation with the United States and Japan, as North Korea ratcheted up harsh rhetoric against Seoul.Last month, the three countries fully activated a system to share North Korean missile warning data in real-time and approved a multi-year plan for trilateral exercises as outlined by their leaders during their Camp David summit in August."We now face the gravest global security environment since the Cold War," Defense Minister Shin Won-sik said in a security conference in Seoul, citing North Korean leader Kim Jong-un's latest war of words.Kim threatened to annihilate South Korea if Seoul attempts to use force against North Korea, calling South Korea his country's "principal enemy," the North's official Korean Central News Agency said.Source: Yonhap News Agency