AFTER MUCH HAGGLING, Poland has signed a Memorandum of Understanding (MOU) with the United States to develop and deploy elements of a ballistic missile defense system on its territory, for the ostensible purpose of deterring and if necessary defeating an Iranian missile attack against European NATO states. Russia for its part has insisted that any such missile defense system is directed against itself, and therefore inherently destabilizing.

Some have seen Poland's foot dragging on the MOU as due to a fear of offending Russia, which provides the bulk of Poland's natural gas supplies and which still poses a military threat. Having recently visited Poland to meet with representatives of the Polish military, the Ministry of Defense and the Ministry of State, I do not believe that this was actually the case. Rather, the Poles were driving a hard bargain to ensure a more "equitable" relationship under the MOU, meaning, in practical terms, technology transfer, workshare in the program, and trade concessions with the United States. It is not clear whether Poland got everything that it wanted, but it is clear that the signing of the MOU at this particular time is no accident, but a response to the Russian invasion of Georgia. This is Poland's way of showing that Russia's attempt to intimidate its near neighbors is not going to succeed, and specifically, that Poland is not afraid of the Bear. In return, Russia is once again threatening Poland's natural gas supplies, while Russian generals fulminate and speak of dire military consequences.

But does the proposed system have any real capability against Russian ballistic missiles? The United States, NATO, and Poland have steadfastly insisted no, but a more accurate answer might be, "It depends."

Whether a missile defense system deployed in Eastern Europe can be used against incoming Russian missiles depends on a number of factors, of which the most important is the siting and orientation of any early warning and surveillance radars. These tend to be large, fixed billboard arrays that cover one particular azimuth. If the array built in Poland is pointed to the southeast (towards Iran), then it will not be properly positioned to detect Russian missiles, most of which would come from the northeast. Of course, once you have emplaced one array, it's a pretty simple matter to build a second one, which placed at right angles to the first, will provide 180 degree coverage.

The second critical factor is the capabilities of the interceptor missile and its fire control radar. Essentially, the farther the fire control radar can see, the sooner the interceptor can be launched. The faster the interceptor, the farther down range it can intercept the incoming missile. The longer the range of a ballistic missile, the higher its reentry velocity, hence the faster the interceptor needed to shoot it down. The Ground-Launched Midcourse System (GLMS) on which any presumptive European missile defense system would be based is designed to intercept fairly slow and primitive North Korean and Chinese missiles. They would probably do very well against Iranian missiles, which in any case are derived from North Korean models. On the other hand, how well they would do against a modern Russian ICBM like the Topol-M is open to question.

However, most of the missiles Russia would direct against its near-neighbors, such as Poland, Ukraine, Bulgaria, Romania, or Georgia, are likely to be short- and medium-range types, because hitting those countries doesn't require the range of an ICBM. The type of missile defense system being deployed in Eastern Europe is not designed to deal with these so-called "theater" ballistic missiles, although the early warning and surveillance radars would be an essential part of any theater defense architecture by providing early detection that could be used to cue fire control radars.

The United States has developed and is on the verge of deploying the Theater High Altitude Air Defense System (THAADS), a deployable (i.e., truck mounted) system consisting of mobile launchers, tracking and fire control radars, a mobile command center, and a powerful solid-fuel interceptor equipped with a kinetic kill vehicle. This falls in both size and capability somewhere between GLMS and the smaller Patriot PAC-3 missile system.