YEONPYEONG ISLAND, South Korea — South Korean attack helicopters screamed through the skies above the Koreas' disputed Yellow Sea waters Wednesday in a display of power exactly a year after North Korea launched a deadly artillery attack on a front-line island.

The South's military staged drills involving aircraft, rocket launchers and artillery guns to send a strong message to North Korean rivals stationed within sight just miles (kilometers) away, and to their authoritarian leader, Kim Jong Il.

The exercises off Baengnyeong Island represent far greater firepower than the South Korean military mounted last year in response to the barrage of artillery showered on military garrisons and fishing villages on nearby Yeonpyeong Island, Joint Chiefs of Staff spokesman Lee Bung-woo said Wednesday.

South Korea is prepared to "crush the enemy," Joint Chiefs of Staff Chairman Jung Seung-jo said Tuesday.

South Korea's delayed response to the shelling at the time — the first on a civilian area since the three-year Korean War ended with a truce in 1953 — drew heavy criticism and concern that Seoul was unprepared for a North Korean provocation. The defense minister resigned, and successor Kim Kwan-jin has pledged a fierce air strike if the North stages another attack.

Two construction workers and two marines were killed, dozens of homes decimated and scores evacuated to the mainland.

Pyongyang blamed Seoul for provoking the attack, saying it struck after warning the South not to carry out live-fire drills in waters both Koreas claim as their territory.

"The pursuit of continued military confrontation and war will eventually bring about the fate of devastation," North Korea's main Rodong Sinmun newspaper said Wednesday, again accusing South Korea of provoking the attack.

North Korea disputes the maritime border drawn by the U.N. at the close of the war, and three deadly naval gunfights have taken place in the Yellow Sea waters since 1999. South Korea also holds North Korea responsible for the sinking of one of its warships in March last year; 46 sailors were killed. Pyongyang denies involvement.

In the past year, South Korea has spent millions of dollars to beef up its arsenal in the Yellow Sea, installing additional radars, setting up a separate defense command and deploying precision-guided rockets designed to take out North Korea's hidden coastal artillery.

Ceremonies on Yeonpyeong Island and at the National Cemetery in Daejeon, south of Seoul, were somber on a cold day.

Residents of the island, which lies just 7 miles (11 kilometers) from North Korean shores, laid flowers at statues erected to commemorate the four dead; a balloon carrying a banner with their portraits floated up into the sky.

At the National Cemetery, Prime Minister Kim Hwang-sik joined the families of the South Koreans killed in the attack for a solemn tribute.

In Seoul, North Korean defectors denounced North Korean leader Kim Jong Il.

"The Yeonpyeong Island attack last year clearly showed that it is totally wrong to think that Kim Jong Il and his regime can change," Seo Jae-pyoung, a North Korean defector, said at a rally of about about 100 people who gathered in Seoul to denounce last year's shelling.

Since the attack a year ago, however, there have been signs that animosities between the rival Koreas are easing, with diplomats seeking to resume North Korean nuclear disarmament talks.

South Korean President Lee Myung-bak told officers that he was sorry North Korea has not yet apologized for the shelling, according to the presidential Blue House. Lee paid a visit Wednesday to a military command that handles the defense of the Yellow Sea area.

He said he expects Pyongyang to apologize if North Korea wants to improve the relations between the two Koreas.

Associated Press writers Sam Kim and Hyung-jin Kim contributed to this report from Seoul, South Korea.