North Korea kept up its harsh rhetoric Friday, indicating that it saw upcoming military exercises as fresh provocation. US Gen. Walter Sharp toured the island area attacked by the North on Tuesday.
North Korean attack presents America with a sudden and serious geopolitical challenge. The overriding US goal is to prevent further escalation of the conflict.
South Korea said Wednesday it will blacklist 102 Iranian firms and 24 people in response to US pressure to sanction Iran over its nuclear program.
Secretary of State Hillary Clinton goes to South Korea Wednesday. But Friday's visit to Seoul by China's premier may do more to determine whether tensions keep rising between North Korea and South Korea.
The Pentagon announced Monday that it will conduct two joint naval exercises with South Korea in response to confirmation that North Korea was responsible for the warship Cheonan sinking.
The recent seizure of an illegal weapons shipment from North Korea in Thailand was praised. But analysts wonder how many weapons shipments sneak through.
Obama is expected to receive a warm welcome in South Korea, where top issues on agenda are North Korea talks and a free trade agreement.
The US has long suspected that Pyongyang had this kind of nuclear program.
The former president was in Pyongyang Tuesday seeking the release of two American journalists. But talks could go beyond that.
The commander of US forces in South Korea says the North would likely use roadside bombs and other insurgent strategies in a ground war.