North Korea said Thursday it was "fully ready" for war with South Korea, stepping up its rhetoric hours before US Secretary of State Hillary Clinton was scheduled to arrive in Seoul. "The Lee Myung-Bak group of traitors should never forget that the Korean People's Army is fully ready for an all-out confrontation," a spokesman for the army General Staff said, referring to the South Korean president. The statement to the communist North's official Korean Central News Agency (KCNA) was the latest in a series of increasingly strident threats against the conservative government in Seoul which have raised cross-border tensions. South Korean Defence Minister Lee Sang-Hee has said a limited naval clash may break out around the two countries' disputed border in the Yellow Sea known as the Northern Limit Line. There were bloody naval clashes in 1999 and 2002 around the line.