South Korea will conduct a large scale military exercise on its east coast ahead of the 2012 Seoul Nuclear Security Summit, official sources said Wednesday.

The combined arms exercise involving Army, Air Force and Navy units will be carried out from noon through 9 p.m. Thursday with a focus on countering threats by a North Korean patrol vessel and submarine.

Military sources said the drill will involve a mock incursion by a North Korea patrol vessel in Goseong, about 225 kilometers northeast of Seoul, while the submarine exercise will take place near a port in Yanyang about 215 kilometers from the capital city.

Both exercises will involve North Korean vessels crossing the northern limit line (NLL), the de facto sea border between South and North Korea.

The violation of the NLL will be countered by shore-based artillery fire and use of South Korea's anti-submarine assets such as Lynx helicopters and other airborne attack platforms.

In addition, the military and local police plan to beef up their anti-terrorism stance by conducting an exercise to apprehend North Korean agents who try to infiltrate the country from the sea.

The training maneuver is timed to check the preparedness of the country's military and law enforcement agencies to deal with unexpected developments as Seoul prepares to host the global nuclear summit on March 26-27.

(Yonhap News)