SEOUL, South Korea — South Korean troops pushed ahead with naval firing drills Monday, a day after North Korea warned such exercises would aggravate already high tensions between the rivals following the North's deadly shelling last month of a front-line South Korean island.

South Korea's army began firing artillery into the waters off the divided Korean peninsula as part of weeklong drills set to continue thorough Sunday, South Korean army and Joint Chiefs of Staff officers said.

The officers, who spoke on condition of anonymity citing office rules, said the drills were to take place at nearly 30 sites, but none of Monday's exercises were near the disputed western sea border between the Koreas where last month's attack took place. The navy said warships were to join the drills later this week.

South Korea's military and Defense Ministry declined to provide further details on the drills.

Tensions have soared since Nov. 23, when North Korea rained shells on Yeonpyeong Island, killing four South Koreans, including two civilians. The North said South Korea first fired artillery toward its territorial waters. South Korea says it fired shells southward, not toward North Korea, as part of routine exercises.

Deadly skirmishes occur periodically along the disputed maritime border, but the latest assault on Yeonpyeong, home to both fishing communities and military bases, was the North's first to target a civilian area since the 1950-53 Korean War.

On Sunday, North Korea lashed out at South Korea for causing "uncontrollable, extreme" tension on the peninsula, pointing to the planned firing drills and what it called South Korea's "frantic provocations."

"The South Korean puppet group, far from drawing a lesson from the deserved punishment it faced for its reckless firing of shells into the territorial waters of the (North Korea) side around Yeonpyeong Island, is getting more frantic in military provocations and war moves," the North's official Korean Central News Agency said.

A KCNA dispatch warned that a war between the Koreas would disturb regional peace and security.

South Korean Defense Minister Kim Kwan-jin said last week that jets would bomb the North if it stages another attack. Kim took office Saturday, replacing a predecessor who resigned amid criticism that South Korea's response to the shelling was too slow and weak.

Despite the recent attack, the Defense Ministry believes it's unlikely North Korea would launch a full-scale war because it could not wage a conflict for long and because of South Korea's solid military alliance with the United States, Yonhap news agency reported Sunday citing the military.

The Yeonpyeong attack came eight months after the sinking of a South Korean warship blamed on a North Korean torpedo attack — also near the maritime border. Forty-six sailors were killed. North Korea has vehemently denied involvement.

The Korean War ended with an armistice, not a peace treaty, technically leaving the two countries still at war. The U.S. stations 28,500 troops in South Korea to deter potential aggression from North Korea.