South Korea defense chief says North Korea 'unstable'

South Korea's defense chief said Monday the country should bolster its security in case of an attack from North Korea as ties between the two countries deteriorate. Tensions on the Korean peninsula have been high since a new pro-US, conservative government took office in Seoul in February. Earlier this month, North Korea restricted traffic across their shared border in protest against Seoul's hard-line policy toward Pyongyang. The restriction forced the suspension of two remaining rapprochement projects between the Koreas - a cross-border train service and a tour to a North Koran border town. On Monday, South Korean Defense Minster Lee Sang-hee told top military generals that South Korean troops must be prepared to take up arms at any time to cope with possible armed provocation from the North.