North Korea's Nuclear Test: Motivations, Implications, and U.S. Options [Updated December 12, 2006] [open pdf - 145KB]
From the Summary: "On October 9, 2006, North Korea announced it conducted a nuclear test. After several days of evaluation, U.S. authorities confirmed that the underground explosion was nuclear, but that the test produced a low yield of less than one kiloton. As the United Nations Security Council met and approved a resolution condemning the tests and calling for punitive sanctions, North Korea remained defiant, insisting that any increased pressure on the regime would be regarded as an act of war. China and South Korea, the top aid providers to and trade partners with the North, supported the resolution itself, but have been unwilling to cut off other economic cooperation and aid considered crucial to the regime. The sanction regime depends heavily on individual states' compliance with the guidelines. Economists argue that the only definitively effective punishment on North Korea would be the suspension of energy aid from China, which reportedly supplies about 70% of North Korea's fuel. Determining the motivations of a government as opaque and secretive as North Korea is exceedingly difficult, but analysts have put forth a range of possibilities to explain why the Pyongyang regime decided to test a nuclear weapon. The most fundamental U.S. goals of the confrontation with North Korea are to prevent the proliferation of weapons of mass destruction and to prevent an attack - either nuclear or conventional - on the United States or on its allies in the region."
CRS Report for Congress, RL33709