South Korean and US troops began military drills yesterday, as North Korea warned that the exercises could trigger a nuclear war on the divided peninsula.
Despite the North Korean threats, South Korea and the United States went ahead with their first major combined military exercises since the North shelled a frontline South Korean island in November, killing four people.
That barrage came eight months after 46 sailors were killed when a South Korean warship sank, which Seoul blamed on a North Korean torpedo attack. Pyongyang denies involvement.
Animosity over the bloodshed drove ties between the two Koreas to one of their lowest levels in decades.
About 12,800 American troops and 200,000 South Korean soldiers and reservists were expected to participate in the drills.
Hours after the exercises started, North Korea reacted. "It's an anti-national scheme aimed at prolonging the stage of confrontation and tension to realise a plot to start a northward invasion," the North's official Rodong Sinmun newspaper said. "The danger of a nuclear war on the Korean peninsula is deepening."
Pyongyang's Korean Central News Agency reported earlier that the North had promised "relentless retaliation" to the drill, which would turn Seoul into a "sea of fire".