The collapse of the Soviet Union has heightened alarm over the fate of the thousands of nuclear weapons deployed across its former territories. The worry is that the new states' pledges to disarm may be overturned and central control weakened by economic hardship and the likely conflict between the new nations. But the political changes also bring great opportunities. William Walker writes that there is now the chance to de-nuclearize much of Eurasia and to achieve deep cuts in the US and Russian arsenals. The Soviet Union's demise has shown that economic development not the possession of nuclear weapons is the main guarantor of the security of states.