The possible deal between the United States and North Korea, discussed last month in Berlin by Assistant Secretary of State Christopher Hill and his North Korean counterpart, Vice Foreign Minister Kim Gye-gwan, is expected to be ratified at Six-Party Talks later this week in Beijing. If the North freezes but does not dismantle its nuclear program, the threat of another nuclear crisis will persist; to achieve lasting success, all parties to the talks must insist on the irreversible denuclearization of the Korean Peninsula.