If suspicions are proven correct, there are few good policy options available for a response. There is no sense in South Korea retaliating with military force since the costs far outweigh the possible benefits.

Mr. Kim habitually travels by train and his visits are generally not confirmed until he has returned to North Korea. He is not believed to have been abroad since a 2006 visit to China. China is North Korea's main trading partner and the country perceived to have the most influence on the communist state.

You would have to believe in miracles to think that North Korea would ever give up its nuclear weapons program. That’s the view of a distinguished professor from China who talks with an air of authority that seems to reflect an insider’s understanding of what’s really going on in the North Korean capital of Pyongyang.

While a visit to the reclusive Democratic People's Republic of Korea is next to impossible for most, Pyongyang offers casual diners a window into Kingdom Kim, an elaborate combination of food and culture from north of the 38th parallel.

Researchers from Stanford University and a consortium of nonprofit organizations have been working side by side with colleagues from the North Korean Ministry of Public Health...to help set up the isolated nation's first laboratory capable of growing the mycobacterium that causes tuberculosis (TB) and detecting drug-resistant strains.

On June 7, North Korea's highest court sentenced two American journalists to 12 years of hard labor, a sentence more severe than most had predicted.