SEOUL, March 11 (Yonhap) -- South Korean and U.S. troops launched their annual joint drills on Monday, amid military tension after North Korea threatened to scrap the 1953 Armistice Agreement that ended the Korean War and make a pre-emptive nuclear attack against the allies.
The two-week computer simulated exercise, called Key Resolve, mobilizes 10,000 Korean forces and 3,500 American personnel to test various scenarios in which South Korea's Joint Chiefs of Staff (JCS) plays a leading role in conducting operations, the JCS said. Such practice is needed as Seoul prepares to regain its wartime operational control (OPCON) from Washington at the end of 2015.
Tensions on the Korean Peninsula are nearing a boiling point as Pyongyang strongly denounced the annual drills, vowed to scrap the Armistice Agreement and canceled a cross-border hotline on the heels of the joint drills and tougher U.N. sanctions over its third nuclear test on Feb. 12.
Military officials in Seoul expect the North will carry out a large-scale military drill along its eastern front in Gangwon Province this week.
As units at North Korean artillery bases on the western border islands have stepped up drills and placed artillery cannons where South Korea can easily see them, troops in the South have been placed on high alert to detect any signs of provocations, military officials said.
"South Korean and U.S. forces have strengthened surveillance and readiness on North Korea as it could launch provocations during the Key Resolve and after the training period," a senior military official at the Joint Chiefs of Staff said.
North Korea has set no-fly and no-sail zones off its east and west coast, fueling speculations that it may fire off short-range missiles during the Key Resolve, which runs through March 21.
About 28,500 American troops are stationed in South Korea.