Pyongyang is ramping up its nuclear and missile programs after a successful rocket launch Feb. 7. US officials warn that the North is trying to obtain weapons-grade fissionable material from a previously shuttered reactor.
North Korea often threatens to attack the US. The anniversary of the ruling party's founding on Oct. 10 could be used as a stage for a missile or nuclear test.
One benefit of the recent shelling that heightened tensions across the demilitarized zone are the highest level negotiations between Seoul and Pyongyang in many years.
Kim Jong-un's regime gave South Korea 48 hours to stop broadcasting anti-North loudspeaker messages across the demilitarized zone.
Envoys from the US, South Korea, and Japan met Wednesday to discuss ways of curbing North Korea's nuclear ambitions amid concerns of growing instability in the isolated nation.
North Korean defense minister Hyon Yong-chol was killed in front of hundreds of spectators for a variety of offenses, according to South Korea's spy agency. He was the fourth defense minister in 2-1/2 years.