SEOUL, South Korea - North Korea threatened Thursday to turn Seoul's presidential palace office into a "sea of fire," stepping up its rhetoric one day after South Korea conducted large-scale military drills near a front-line island attacked by North Korea last year.On Wednesday, South Korea mobilized aircraft, rocket launchers, artillery guns and naval boats for the first anniversary of the artillery attack on a military garrison and fishing community on Yeonpyeong Island in the Yellow Sea. Two marines and two construction workers were killed in the attack, the first on a civilian area since the 1950-53 Korean War.
A similar "sea of fire" threatens to engulf Seoul's presidential Blue House if South Korean forces fire a single shot into North Korean territory, the North's People's Army warned in a statement from Pyongyang.
"They should not forget the lesson taught" by the Yeonpyeong shelling last year, said the statement carried by the official Korean Central News Agency.
The North has issued similar threats over years at times of tension with South Korea.
The Korean peninsula remains in a technical state of war because their conflict ended in a truce, not a peace treaty. However, North Korea disputes the maritime border drawn by the U.N. in 1953, and the waters have been a flashpoint for violence over the years.
Pyongyang accuses Seoul of provoking last year's attack, saying it struck after warning the South not to hold live-fire drills in the disputed waters.
Since then, South Korea has spent millions of dollars beefing up its arsenal. Joint Chiefs of Staff chairman Jung Seung-jo said his forces would "crush the enemy" if they strike again.