By Ted Galen Carpenter, North Korea’s continuing development of nuclear weapons is one of the most serious security challenges the United States faces.  The most recent six-party talks (China, Russia, Japan, South Korea, North Korea, United States) made, at best, incremental progress toward a solution to the crisis. Throughout the negotiations, the U.S. goal has remained the same: a complete, verifiable and irreversible end to North Korea’s nuclear program. North Korea’s continuing development of nuclear weapons is one of the most serious security challenges the United States faces.  The most recent six-party talks (China, Russia, Japan, South Korea, North Korea, United States) made, at best, incremental progress toward a solution to the crisis. Throughout the negotiations, the U.S. goal has remained the same: a complete, verifiable and irreversible end to North Korea’s nuclear program.