North Korea and South Korea have both raised the stakes in a Yellow Sea confrontation, with each side wanting to save face.
Top US officials appear to be pressing China to do more to rein in North Korean aggression. Meanwhile, the South held a major civil defense drill Wednesday.
Even though US envoy to North Korea Stephen Bosworth gave no hint of military escalation, he's gone to Seoul and Tokyo seeking support to deescalate North Korea's nuclear program.
US envoy to North Korea Stephen Bosworth arrived in Seoul Sunday to meet with South Korean officials to discuss how resume six-party talks on denuclearizing North Korea.
North Korea said Tuesday that it has reprocessed 8,000 nuclear fuel rods – perhaps enough to build another nuclear bomb. US officials say this was a violation of North Korea's commitments to nuclear disarmament talks.
Destruction of its nuclear cooling tower was important but largely symbolic.