A top South Korean official dismisses China's nuclear negotiator as "incompetent." A Chinese envoy mocks North Korea as a "spoiled child."

After a major escalation of sporadic skirmishes between the rival Koreas, an international effort is trying to rein in rising tensions. But U.S. diplomatic memos leaked this week call into question whether regional powers — most notably China — have any insight into or influence over enigmatic and defiant North Korea.

South Korea's military drill last week from an island along a disputed maritime border sparked a North Korean artillery attack that killed four South Koreans and wounded 18 others. U.S.-South Korean war games — including the presence of the aircraft carrier USS George Washington in the waters to the south — are threatening to draw a new round of North Korean fire.

China is pressing for an emergency meeting in the coming days to discuss the attack and ways to defuse tensions, saying the session should be convened by the two Koreas, China, Russia, Japan and the United States — the members of the stalled North Korean nuclear disarmament talks.

"China consistently supports dialogue between the North and South sides of the Korean peninsula to improve their relations," Chinese Foreign Ministry spokesman Hong Lei said Tuesday.