President Obama announced on September 17 that he will scrap the Bush administration’s plans for a missile defense system in Poland and the Czech Republic, and instead deploy a redesigned system intended to intercept shorter-range Iranian missiles. Defense Secretary Robert M. Gates said the new system would put defenses in place seven years earlier than the Bush plan, which has strained relations with Russia.

What are the consequences of President Obama’s decision? Will the alternative — deploying smaller missiles, at first aboard ships and later elsewhere in Europe or in Turkey — work?

Getting Russia Onboard

The most immediate outcome of President Obama’s decision to replace the ground-based interceptors and radars in Poland and the Czech Republic, respectively, with Aegis-based missiles and x-band radars is to provide more breathing room for U.S. -Russian strategic arms control negotiations. The arms control negotiations need to produce agreement before December 2009, when the START treaty expires, and the Russians have continued to complain about George W. Bush’s decision last year to deploy ground-based missile defense systems in Europe.

This link to the arms talks may have been regrettable but unavoidable. Given that the administration was likely to overturn the Bush missile defense deployments anyway, it may be good timing in terms of getting the most mileage from this concession. If it is true that Iranian long-range missile development has been moving more slowly than forecasted — and there is no reason not to believe that, since their capabilities in this area have been overestimated for more than a decade — then deploying a more flexible system against short- and medium-range missiles on an earlier timeframe makes sense.

The issue then remains what options the U.S. and Europe will seek if or when the Iranians actually do deploy a longer range ballistic missile. Will it be a mobile ground-based interceptor, which Boeing floated this summer? Or will relations with Russia in the future prove to be less of an impediment to fixed-missile defense sites? Better yet, will the threat of an Iranian nuclear-tipped missile have faded from view?

One area that absolutely requires Russia’s undivided attention and cooperation is persuading Iran to step back from the nuclear abyss. President Obama knows that. And if a change in missile defense deployments helps that happen, so much the better.