Later tonight - Thursday morning in Asia - the South Koreans are expected to drop a long-expected shoe and unveil the evidence that a North Korean torpedo sank a South Korean patrol ship last March, killing 46 sailors.
North Korea has already denied it, but the evidence recovered after the sunken ship was raised from the bottom of the Yellow Sea is compelling. Traces of explosives and shards of metal match the materials used in a North Korean torpedo that fell into South Korean hands several years ago. The U.S., Britain and Australia - all of which helped in the investigation - are all prepared to back up the findings. Only Sweden, which also sent investigators, is a reluctant partner in blaming the North Koreans.
There was never much mystery about who done it. The real mystery is what to do about it.
Sinking another nation's ship is an act of war. But the North and South are still technically at war, observing only an armistice which ended the Korean War. No one expects this incident to trigger a full-scale war. It would be a disaster for North Korea, South Korea, the U.S. and China. The North would lose, the South would suffer horrendous casualties (Seoul is within range of North Korean artillery), and the U.S. (which still has tens of thousands of troops there) and China would have to pick up the pieces.
But South Korea cannot simply ignore the sinking of one of its ships and the loss of life that went with it. Economic reprisals seem to be the weapon of choice. The North and South do a small amount of business, but it would take international sanctions enacted by the United Nations to have a maximum impact, possible only if China - North Korea's chief trading partner and benefactor - goes along. China is reluctant to take any action that might trigger the total collapse of North Korea since it would almost certainly result in streams of refugees coming across the border.
In other words, North Korea might get off lightly for what amounts to murder. It wouldn't be the first time, and nobody seems to have a good idea how to make it the last.
David Martin is CBS News' National Security Correspondent. You can read more of his posts in World Watch here.