JOIN USThe US president said North Korea's recent nuclear blast and other behavior tested the limits of diplomacy.
The threat by the communist government's National Peace Committee came as many worried that a sea clash could quickly escalate into a major confrontation amid soaring tensions over the North's recent nuclear and missile tests. Deadly battles occurred in the area in 1999 and 2002.
Without providing specifics, the North's official Korean Central News Agency alleged that the patrol boats were crossing into its territorial waters on daily missions. It said such aggressors would be dealt "merciless punishment that will be beyond imagination," and that "war moves will be shattered to smithereens."
South Korea rejected the North's allegation. Just two days earlier, the South accused the North of sending a patrol boat across its sea border in the same area. The boat turned back without incident after a 50-minute standoff with the South's naval ships, the military said.