North Korea warned yesterday that US-South Korean cooperation could bring a nuclear war to the region, as the South began artillery drills amid lingering tension nearly three weeks after the North’s deadly shelling of a South Korean island.

The South’s naval live-fire drills began yesterday and will run through Friday at 27 sites. The regularly scheduled exercises are getting special attention following the North’s artillery attack on front-line Yeonpyeong Island that killed two South Korean marines and two civilians.