North Korea's military warned Tuesday that it would mercilessly avenge any breach of its territorial sovereignty by South Korea or the United States during the ongoing anti-submarine drills in the Yellow Sea.

The Southwestern Front Command of the Korean People's Army said it has directed its troops to immediately strike back in case even a single shell falls in its territorial waters, the Korean Central News Agency (KCNA) said.

The anti-submarine drill that began Sunday and runs through Friday comes in the wake of the two-month-long joint Foal Eagle military exercise carried out by South Korea and U.S. forces.

Pyongyang's official news agency warned that if South Korea or the U.S. responds "recklessly" to the North's counter strikes, prompt actions by rocket forces deployed in the southwestern sector will turn the five islands in the Yellow Sea into a "sea of flames." The five islands under South Korean control are Baengnyeong, Daecheong, Socheong, Yeonpyeong and Udo.

It said all units and sub-units of the military in the region will simultaneously start military actions in accordance with operation plans ratified by the supreme command.

The North had set up the Southwestern Front Command last September that is charged with all shore batteries and multiple rocket launcher units in South Hwanghae Province and islands along the northern limit line that acts as the de facto sea border between the two Koreas.

The naval maneuver aims to sharpen anti-submarine warfare capabilities and includes live-fire exercises. The U.S. has sent a Los Angeles-class attack submarine to take part in the exercise.

Advanced Aegis destroyers and P-3C Orion anti-submarine aircraft are involved in the drills.

Pyongyang in addition said that the United States has sent a carrier battle group to carry out naval exercises in the East Sea starting later in the week.

"They are intensifying the anti-North war drills with a reinforced nuclear force in a bid to ignite nuclear war at any cost," the KCNA said.

Related to the latest warning, the political bureau at the North's National Defense Committee said in a statement released over the weekend that if Seoul wants normal operations to resume at the Kaesong Industrial Complex, it has to first stop all provocations. The industrial complex in North Korea, which first began churning out products in late 2004, halted all operations in early April after the North withdrew all of its workers from the joint venture.

South Korea's Ministry of Defense brushed off the statement and made clear it had no intention of calling off the combined naval exercise. (Yonhap News)