From Steven Pifer, Brookings:  The Russian concern has an understandable basis in principle:  if U.S. missile defenses continue to grow in numbers and quality, at some future point they could undermine the balance in strategic offensive forces between Russia and the United States.   But it is difficult to see that happening in the next decade or two.  An optimistic projection of the maximum number of ground-based interceptors and Standard Missile (SM-3) Bloc IIB interceptors, which will have some capability against intercontinental ballistic missiles, would be at most 100 in 2023.  That number would pose little real threat to the hundreds of warheads on Russian intercontinental ballistic missiles and submarine-launched ballistic missiles, to say nothing of the decoys and other countermeasure carried by those missiles. . . .

If Moscow is prepared to move off of its requirement for a legal guarantee, and Washington and NATO are prepared to show some greater transparency and flexibility in their approach, one can see the elements of a compromise that would allow agreement on a cooperative NATO-Russia missile defense arrangement. . . .

Adapting the U.S./NATO Approach.  The United States and NATO could introduce three additions or modifications to their current approach to missile defense and missile defense cooperation.

First, the United States should commit to provide Russia an annual declaration regarding U.S. missile defense capabilities and future plans.  The declaration would specify for each key element of U.S. missile defenses—including, at least, ground-based interceptors (GBIs), SM-3 interceptors (broken down by Bloc IA, Bloc IB, Bloc IIA and Bloc IIB), GBI launchers, SM-3 land launchers, associated radars and warships equipped to carry SM-3 interceptors—the current number and the planned maximum number for each year in the coming ten years.  For example, the line in the notification for the SM-3 Block IB would read as follows:*

The United States would further commit to provide Russia advance notice of any change in its planned maximum numbers.  For example, for changes in the planned maximum numbers of SM-3s, it could be 18-24 months’ advance notice, as it appears to take about two years from the time a decision to purchase an SM-3 is made for the contract to be concluded and for the interceptor to be built and delivered to the military.  For changes in the planned maximum number of warships, the advance notice would be longer.

Russia is also developing its missile defense capabilities.  It would be useful for Russia to provide the United States parallel declarations regarding its current capabilities and future missile defense plans.

Second, NATO should modify its current position, which appears to be that any cooperative defense with Russia would in no way change NATO missile defense deployment plans.  The Alliance should instead indicate a readiness to consider Russian-proposed changes, provided that those changes do not degrade the ability of NATO missile defenses to defend NATO territory.  For example, under this approach, NATO would be willing to consider a Russian proposal that SM-3 interceptors to be deployed in Poland be relocated from the planned site on the Baltic coast to a military base in southwest Poland if those interceptors could provide essentially the same protection for NATO members from the new site, in particular, for the Baltic states and Norway.

Third, the U.S. government should state unambiguously that, were it to become evident that Iran was not making progress toward having an intercontinental ballistic missile capability, the United States would defer deployment in Europe of the SM-3 Bloc IIB interceptor.  That would be entirely consistent with the concept of the “European phased adaptive approach”—if the Iranian ICBM threat does not materialize, there would be no need to deploy a defense in Europe to counter it. . . .

[T]his compromise would respond to Russian concerns in two important ways.

First, the annual declarations would provide the Russian military a very full and regularly updated picture of U.S. missile defense capabilities and future plans.  The Russian military could compare those capabilities and plans with its current and projected strategic ballistic missile forces.  That would allow the General Staff and Ministry of Defense to determine whether there was, or in the future would be, a serious threat to Russian strategic missiles and to the U.S.-Russian strategic offensive balance (with a parallel Russian declaration, the U.S. military could make its own determination).

Second, although this arrangement would not legally constrain missile defenses, each side would always have the option, if it chose, to make a unilateral statement in response to the other’s declaration.  That statement could include how it might react were the other side to increase its numbers beyond the planned maximum numbers contained in a declaration.  For example, Russia might state that, were the United States to increase the number of SM-3 Bloc IIB interceptors beyond the planned maximum number indicated for a certain year, it could consider the strategic offensive balance endangered and might take corresponding measures.  Such corresponding measures could include withdrawal from the New START Treaty or a from a successor treaty that further reduced nuclear arms.  Moscow could, if it wished for political purposes, portray that as something of a de facto limit.  At the least, a Russian statement would indicate to Washington that there could be consequences if U.S. missile defenses increased beyond the declared number. . . .

This approach offers a middle ground for U.S./NATO-Russian agreement on a cooperative missile defense arrangement.  It is possible that Moscow did not want to engage on missile defense in 2012 in part because the U.S. approach to missile defense and missile defense cooperation might have changed radically if a Republican with very different ideas on missile defense became president in 2013.  It is now clear that Barack Obama will remain in the White House for the next four years.  It is now time to resolve differences over missile defense.  The elements of a compromise for a cooperative NATO-Russia missile defense arrangement are evident.  The question is whether the sides have the political will to reach that compromise.

Steven Pifer is director of the Brookings Arms Control Initiative and a senior fellow in the Center on the United States and Europe.  (photo: Carolyn Kaster/AP)