The findings of South Korea's internationally staffed inquiry, which concluded that a North Korean torpedo sank the South Korean corvette Cheonan, killing 46 of the 104 crew, in the Yellow Sea on March 26, have caused relations across the 38th parallel to sink to their worst in over a decade. The South (the Republic of Korea, or ROK) has banned North Korean ships from Southern waters, re-routed all commercial flights around Northern airspace, and started anti-submarine naval exercises. Cross-border family ties have been severed and the South will maintain only humanitarian aid for North Korean children. For its part, North Korea (the Democratic People's Republic of Korea or DPRK) denies responsibility for the sinking, and has cut other Southern links until ROK President Lee Myung-bak leaves office. The DPRK, furthermore, is expelling eight South Korean officials from the Kaesong joint industrial zone. Its leader, Kim Jong-il, has reportedly told his military to prepare for war. Pyongyang has also threatened to fire on Southern military facilities, which have resumed propaganda broadcasts. Predictably, the protagonists' main allies, the United States and China, have got involved. President Obama has declared “unequivocal” support for Seoul; his administration supports taking the matter to the U.N. Security Council; and the Pentagon has announced plans for joint U.S.-South Korean naval exercises. Secretary of State Hillary Clinton, in Seoul after talks in Beijing, has called on the rest of the world to respond. China, however, is cautious, regretting the sinking and agreeing only to consult with Washington over it.

Since taking office, Mr. Lee has been consistently hostile towards the North, even criticising his predecessors' policy of engagement. He has also rejected the joint investigation proposed by Pyongyang into the sinking. Both governments indicate they will not initiate an attack, but the situation is potentially explosive. With North-South communications in limbo, any border skirmish can rapidly escalate and the situation spin out of control. Washington's posture and statements may encourage the South to become more confrontational. It is, moreover, possible that Mr. Lee meant to cast a shadow over Ms Clinton's China talks and boost his own party for imminent regional elections. Fortunately, Beijing has considerable leverage here. It has influence with Pyongyang; it can veto any one-sided U.N. Security Council action; and the U.S would need its support for sanctions on Iran. The two Koreas must resolve this crisis through constructive engagement and the big powers should work resolutely to end it.

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