Seoul:
The United States and South Korea began naval exercises on Sunday that were meant as a warning to North Korea for recent provocations, including last week's deadly artillery attack on a island populated by South Koreans in the Yellow Sea.
At the same time, China stepped up its diplomatic efforts to cool tempers in the region, with a senior envoy holding a meeting on Sunday morning with South Korea's president and Beijing announcing that it had invited a senior North Korean official for talks this week.
North Korean artillery was heard Sunday on the island, though no shells landed there and South Korea considered it just a drill, according to a spokesman for South Korea's Joint Chiefs of Staff. The North Koreans also shot off artillery on Friday, after a visit by an American general to the island, called Yeonpyeong.
The announcement of the naval exercises last week raised already heightened tensions, angering both North Korea and its patron, China, and stirring intense speculation in the South Korean news media about whether the North would respond violently.
After the announcement, China warned against "any military act" in its exclusive economic zone without permission, according to the state-run Xinhua news agency. But virtually all the waters to the west of the Korean Peninsula fall within that 200 nautical mile limit. It was not immediately clear if the American and South Korean flotilla, which included the United States aircraft carrier George Washington, had sailed into that area.
China's diplomatic efforts came after days of entreaties from Washington and its allies to exert a moderating influence on North Korea.
The Chinese envoy, state counselor in charge of foreign affairs, Dai Bingguo, met with South Korea's president, Lee Myung-bak, as part of a previously unannounced visit to Seoul, according to a senior South Korean official.
China's diplomatic initiative also included the planned talks with Choe Tae-bok, chairman of North Korea's Supreme People's Assembly, who will pay an official visit to China starting Tuesday.
The United States has hoped that China would use its leverage over North Korea to restrain it from any further attacks, but so far China has not rebuked the North's leaders, at least in public. And when China did finally make a strong public statement late last week on the attack -- the one warning against military actions in its economic zone -- it directed its pique at the United States for the naval exercises.
The show of force was designed both to deter further attacks by the North and to signal to China that unless it reins in its unruly ally, it may see an even larger American presence in the vicinity.
The flurry of diplomacy over the weekend followed days of recriminations by both Koreas. On Saturday, North Korea accused South Korea of using civilians as human shields around military bases on the island. The accusation, reported by the North's official news agency, is apparently an effort to redirect South Korean outrage over the barrage, which killed two civilian construction workers and two South Korean marines.
"If the U.S. brings its carrier to the West Sea of Korea at last, no one can predict the ensuing consequences," the report said, using the Korean name for the Yellow Sea.
Also on Saturday, at least two protests were staged in Seoul that criticized both North Korea's leader, Kim Jong-il, for the attack and South Korea's president for what many here see as the military's failure to make more than a token response.
The bombardment of the island was the first attack on a civilian area since the 1950-53 Korean War, and it enraged the South Koreans far more than previous provocations by the North, including its nuclear weapons tests and the sinking in March of a South Korean warship that killed 46 sailors. Despite the findings of an international investigation, North Korea denies responsibility for the sinking.
The North has said that Tuesday's attack was carried out in response to South Korean artillery drills earlier that day on the island, which sits within sight of the North Korean mainland. On the morning of the attack, North Korea warned South Korea not to conduct the drills.
Citing those warnings, North Korea said it had made "superhuman efforts to prevent the clash at the last moment." It also offered an uncharacteristic show of remorse, calling the civilian deaths "very regrettable."
The comments were apparently an attempt to present the North's view of events to the South Korean public, which has reacted to Tuesday's attack with uncharacteristic vehemence toward the North.