The accomplishment of a post– Strategic Arms Reduction Treaty (START) I nuclear arms reduction agreement by Russia and the United States calls to mind a Chinese character that stands for both opportunity and danger. Post-START success opens the door to further reductions in both states’ nuclear arsenals, and it also creates a possible driver for U.S. and Russian leadership on nuclear nonproliferation. Danger lies in the expectation that post-START political or military success follows automatically from good intentions or less frosty diplomatic demarches.