The pursuit of nuclear arms control has enjoyed something of a renaissance recently, with the signing of the New Strategic Arms Reduction Treaty (New START) in spring 2010 in Prague. Whether that momentum will dissipate after New START or lead to further nuclear arms control agreements depends on several factors:

1. The new U.S. and Russian nuclear doctrines. While there is always some distance between a state’s declared policy and that policy’s implementation, both documents show that, behind their more ambitious disarmament rhetoric, the United States and Russia maintain conservative nuclear policies that make radical nuclear disarmament unlikely— to say nothing of a nuclear-weapon-free world.
    
2. The peculiarities of the recently signed and ratified New START agreement. Among these are the modest cuts stipulated by the treaty relative to its predecessors; the acrimonious ratification debates in both the U.S. and Russian legislatures; and the dim prospects for a follow-on agreement (in sharp contrast to the mood prevailing after past START agreements).
    
3. The dynamics of obsolescence and modernization of U.S. and Russian strategic offensive forces. The United States should have little problem cutting its forces to get below New START’s limits. Russia, however, will have problems, not in reducing its numbers, but in raising them to treaty ceilings, due to their removal of obsolete weapons from service and slow deployment of new systems. Either Russia can negotiate a New START follow-on treaty with even lower ceilings or it can accelerate the development and deployment of new systems. While the former is obviously a more attractive alternative, it would require the United States and Russia to resolve many thorny arms control issues, such as ballistic missile defense, conventional strategic weapons, and tactical nuclear weapons.
    
4. Ballistic missile defense. President Obama’s decision to modify the Bush administration’s ballistic missile defense plans in Central Europe opened the way for New START and eased Russian concerns, even if they could never have been allayed entirely. Moscow believes that U.S. ballistic missile defense programs are ultimately designed to degrade Russia’s nuclear deterrent, and it is far from clear that U.S. proposals to jointly develop such capabilities with Russia would allay those concerns—or that the idea even makes any sense.
    
5. Russia’s perceptions of U.S. conventional strategic weapons. Russian officials are especially concerned about the U.S. Prompt Global Strike concept and do not trust American assurances that such capabilities are only directed at terrorists and rogue states. There has already been some progress made in dealing with these weapons in negotiations, and future progress on this issue will likely depend on legal agreements and confidence-building measures to scale U.S. capabilities in ways that would threaten Russia’s (or China’s) strategic deterrent.
    
6. Joint development of ballistic missile defenses with Russia. This issue could seriously complicate Washington’s and Moscow’s strategic relations with China and India. Officials on both sides would do well to start small and proceed step-by-step, using incremental successes to build the momentum necessary to work through more difficult issues.
    
7. Non-strategic—that is, tactical—nuclear weapons. During the Cold War, the United States and Europe relied on tactical nuclear weapons to counterbalance Warsaw Pact superiority in conventional forces in Europe; today, the situation is reversed, with Moscow relying on tactical nuclear weapons as a counterbalance not only to NATO conventional superiority but also to U.S. strategic nuclear superiority and long-range precision-guided weapons. No one now knows which weapons systems should be categorized as non-strategic, and how limits across regions could be accounted for and verified. In addition, reviving the moribund Conventional Forces in Europe (CFE) Treaty is essential to dealing with the issue of tactical nuclear weapons.

Working through these complicated factors will require painstaking effort by U.S. and Russian diplomats and experts. They will have to move past not just Cold War habits and prejudices but also the mistakes and misunderstandings of the past two decades of post–Cold War history. Commitment to this task will determine whether New START goes down in history as a mere gambit or as the first step of an endgame for U.S.-Russian security competition.