The Nuclear Security Summit process, which concluded recently in Washington, shows what can be achieved when political leaders come together to concentrate on a global problem. The six-year initiative, focused on preventing nuclear terrorism, produced important outcomes on eliminating, minimizing and securing dangerous nuclear and radiological materials.

Unfortunately, however, the nuclear threat is still far from being neutralized. The dangers posed by terrorist groups are growing, as are the risks from competition and conflict between nuclear-armed states. Strong leadership and global cooperation must also be deployed to address other urgent nuclear dangers, particularly the threat of further testing and proliferation of weapons.

There are few bright signs on the horizon. On the contrary, almost every nuclear-armed state is either expanding or upgrading its nuclear arsenal. There are no active negotiations to regulate, cap or further reduce nuclear stockpiles.