North Korea warned Friday that planned U.S.-South Korean military drills are pushing the peninsula to the brink of war as a U.S. military commander headed to an island devastated this week by a North Korean artillery barrage.

North Korea's state news agency said drills this weekend involving South Korean forces and a U.S. nuclear powered supercarrier in waters south of Tuesday's skirmish between the rival Koreas are a reckless plan by "trigger-happy elements" and that the manoeuvres target the North.

"The situation on the Korean peninsula is inching closer to the brink of war," the dispatch from the Korean Central News Agency said.

The comments came ahead of a planned visit Friday by Gen. Walter Sharp, the U.S. military commander in South Korea, to the island targeted by the North Korean attack to show solidarity with ally Seoul.

Four South Koreans — two marines and two civilians — were killed in the hour-long skirmish Tuesday after North Korea unleashed a barrage of artillery on the Yeonpyeong, but the island was quiet Friday morning, with most residents having fled to the mainland.

Earlier, South Korea's president ordered more troops to a front-line island and dumped his defence minister Thursday.

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A resident of Yeonpyeong Island walks through ruins carrying a plastic sheet to cover his shattered windows on Thursday. ((David Guttenfelder/Associated Press))

Washington and Seoul pushed ahead with plans for military drills starting Sunday involving a nuclear-powered U.S. aircraft carrier in waters south of this week's skirmish.

"We should not ease our sense of crisis in preparation for the possibility of another provocation by North Korea," spokesman Hong Sang-pyo quoted South Korean President Lee Myung-bak as saying. "A provocation like this can recur any time."

South Korea's defence minister also tendered his resignation, and CBC reporter Anthony Germain said Kim Tae-young had toured the island just hours before. Kim was criticized following Tuesday's attack by both government and opposition legislators, who demanded his resignation. They also called on military leaders to step down as well.

Pressure on China

Meanwhile, Washington and Seoul ratcheted up pressure on China, North Korea's main ally and biggest benefactor, to restrain Pyongyang.

Chinese Premier Wen Jiabao responded by calling on all sides to show "maximum restraint" and pushed again to restart the six-nation talks aimed at persuading North Korea to dismantle its nuclear programs in exchange for aid. Foreign Minister Yang Jiechi, meanwhile, cancelled a trip to Seoul this week.

The heightened inter-Korean animosity is taking place as North Korea undergoes a delicate transition of power from leader Kim Jong-il to his son Kim Jong-un, who is in his late 20s and is expected to eventually succeed his ailing father.

At an emergency meeting in Seoul, Lee ordered reinforcements for about 4,000 troops on tense Yellow Sea islands, top-level weaponry and upgraded rules of engagement that would create a new category of response when civilian areas are targeted.

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Kim Tae-young, right, who has resigned as defence minister, leaves a memorial altar after offering condolences for two dead marines at a military hospital in Seongnam, south of Seoul, on Thursday. ((Reuters))

Skirmishes between the Korean militaries are not uncommon, but North Korea's heavy bombardment of Yeonpyeong Island was the first naval skirmish since the Korean War to kill civilians.

South Korean troops returned fire and scrambled fighter jets in response, but two South Korean marines and two construction workers were killed and at least 18 others wounded. South Korea has said casualties on the North Korean side were likely significant, but none were immediately reported by the secretive regime.

One South Korean woman told CBC reporter Germain that there were three shellings that lasted 10 minutes each. Germain said it appears it was 10 to 15 minutes until South Korea fired back, and with less force than North Korea used.

Marine Lt.-Col. Joo Jong-wha acknowledged that the island is acutely short of artillery, saying it has only six pieces: the howitzers used in Tuesday's skirmish.

"In artillery, you're supposed to move on after firing to mask your location so that they don't strike right back at you," he told reporters. "But we have too few artillery."

On the streets of Yeonpyeong, some spoke of walls of flame, surreal images of blackened skies, massive dust clouds, and orange-coloured lightning.

"My town was almost burned out," said Noh Myung-san, 56, who was planting trees near a mountain when he heard artillery explosions. "I thought it was an earthquake."

Though North Korea regularly threatens to rain munitions down on its rival, the two Koreas are required to abide by an armistice signed in 1953 at the end of their bitter three-year war.

With files from CBC News