WASHINGTON, Nov. 28 (UPI) -- South Korea and the United States shrugged off dire North Korean warnings Sunday and started four days of naval exercises in the Yellow Sea.
"The drills started around 6 a.m. Sunday with the [aircraft carrier] USS George Washington joining our warships in the Yellow Sea," Yonhap quoted an official at the South's Joint Chiefs of Staff as saying.
The training is taking place off the west coast community of Taean, more than 75 miles south of Yeonpyeong Island, where two South Korean marines and two civilians died in a North Korean artillery attack Tuesday.
The South Korean news agency cited a military source that said U.S. forces were employing a high-tech radar system.
"The Joint STARS system will carry out its mission of closely tracking ground targets in the North Korean military," the source said.
While the joint naval exercises were scheduled before the North's attack, the drills are being ratcheted up, South Korean military officials said.
"The intensity for the Yellow Sea drills will be higher than planned," one official said. "Participating troops will conduct live-fire shooting and bombing drills."
U.S. officials termed the training "defensive in nature," but with the intention of serving as a "deterrence" against North Korea.
Pyongyang issued ominous warnings.
"Escalated confrontation would lead to a war," a North Korean state agency said in a statement issued ahead of the exercises and carried by the North's Korean Central News Agency.
"If the U.S. brings its carrier to the West Sea of Korea at last, no one can predict the ensuing consequences."
The BBC reported North Korea accused the South of using civilians as human shields on Yeonpyeong Island. State-run media in the North said the South was "creating the impression that the defenseless civilians were exposed to indiscriminate shelling from the North," the British network said.
Pyongyang said it was provoked by the South's earlier military exercises and had sent a "telephone notice" the morning of its bombardment "to prevent the clash at the last moment."
The joint naval exercises are directed at deterring North Korea and not China, U.S. Pentagon officials said.
China, a North Korean ally, is known by Washington to disapprove of U.S. involvement with South Korean defense, Yonhap said.
In March, Seoul blamed North Korea for sinking South Korea's Cheonan warship, killing 46 sailors. China refused to blame North Korea directly and watered down the United Nations rebuke to the North.