If 2010 was the year of successes and landmarks for arms control, 2011 was the year that the momentum of the new era slowed, and hard realities were made apparent. By the end of the year, the Comprehensive Nuclear Test Ban Treaty had not been ratified or even seriously discussed, and negotiations on the Fissile Materials Cut-off Treaty remained stuck in the Conference on Disarmament, with no sign of success in the offing. The author takes a look at five events that unfolded in 2011 and that seem certain to cast a powerful shadow in months and years to come. He writes that both the spread of nuclear technology in the Middle East and Southeast Asia and the revision of the export control regime pose a threat to the long-term structure of the global nuclear order. The crisis with Iran continues to present a serious challenge to the Non-Proliferation Treaty regime while raising the risk of a military response. A conference on a Middle East WMD-free zone requires addressing an ambitious objective in the world’s most intractable diplomatic environment. And the impediments to progress in US–Russian relations stifle hopes that further agreements and deeper cuts can be achieved; a deterioration of this relationship could mean serious consequences in the arms control environment. In 2011, no new breakthroughs occurred, the author writes, adding that 2012 could be a much more difficult year.