N. Korea attacks S. Korea ahead of assault anniversary. November. 21, 2013 08:50. .

The South Korean military is closely watching the North Korean military`s moves to build up forces near the Northern Limit Line (NLL), the de factor sea border with the North, and the northwestern frontline islands. According to the South Korean military Wednesday, the North Korean military has deployed upgraded 240-millimeter multiple rocket launchers with increased ranges to units stationed near the South`s Baengnyeong and Yeonpyeong islands. Seoul`s military authorities said that the North has conducted infiltration drills mobilizing submersibles and semi-submersible vessels on the waters north of the NLL.

The North has recently completed fortifying artillery positions at units, including the Mu Island defense unit, near the frontline islands that suffered damage from the South Korean military`s counterstrike at the time of the North`s shelling of Yeonpyeong Island. "We understand that the North Korean military has finished covering all artillery positions and trenches with concrete," said an official at the South Korean military. Recently, the U.S.-based Radio Free Asia reported that the North had given an order to fortify all military installations, including those near the demilitarized zone, following the Mu Island defense unit`s example. In addition, Pyongyang has deployed forward since the second half of last year two attack helicopter squadrons capable of infiltrating at low altitudes into the South while carrying Special Forces troops.

The South`s project to build up military forces on the frontline islands against the North`s additional provocations are in final stages. It has deployed additional 1,200 marines to Baengnyeong Island after establishing the Northwestern Islands Defense Command and 40 K-9 self-propelled guns, up from 10 on all the islands three years ago. In addition, 130 millimeter rocket launchers and the new anti-artillery radars and the Cobra attack helicopters. Seoul also deployed Spike missiles capable of surgically striking the North`s coastal artillery in May and plans to introduce tactical aircrafts for monitoring the North Korean military`s movements over the northwestern islands. The first phase of the fortification project for the troops and equipment on the islands was completed last year, and the second phase project is under way for completion in 2015. "The North Korean military`s provocation threats against the northwestern islands remain the same as they were three years ago," a South Korean military official said. "In the event of another provocation, (the South Korean military) is fully prepared to mercilessly retaliation against the source of the provocation and the supportive and commanding forces by mobilizing all means of strike."