Germany's Angela Merkel understands the threat posed by rogue nations like Iran. Merkel wants to construct a "common position" in Europe regarding missile defense -- escaping the United States versus Russia template and assuring the Kremlin that this will be a cooperative defense system. Merkel believes Europe cannot afford to split on the ABM issue, as it did on the U.S. invasion of Iraq.

Everyone, including the Kremlin, seems to agree that we now face 21st century threats very different from the 20th century's East-West bloc confrontation.

This week, Russian Deputy Foreign Minister Alexander Grushko sent a mixed signal, saying that Russian cooperation with NATO depends "on the choice of final configuration of the layered missile defense system being developed."

The evolving Russian position appears to be a begrudging "yes" to a NATO-European system, a "no" to a U.S. system. Konstantin Kosachev, chairman of the Duma's foreign affairs committee, wrote in the International Herald Tribune on April 6 that "Russia has every reason to be interested in close cooperation in creating Eurasian missile-defense systems." But Kosachev also said Russia and Europe risk "humiliation" by remaining dependent on the United States to run the system.

In other words, Russia wants a strong say in the system's deployment and operation. Never say never -- Russian operational participation could be part of a final deal.

The U.S. Department of Defense says that Iran could have ICBMs by 2015, so there is time to deploy. At the minimum, a Euro-ABM gives the West a "deterrent in place," which creates diplomatic leverage in a crisis. Poland's interceptors are only part of the system envisioned. A "layered" system could include short-range ABMs near European cities. The United States estimates this system would have a 60 percent to 80 percent chance of intercepting an Iranian missile fired at London.

Is that worth the expense and political tradeoffs? Deputy Assistant Secretary of State Mark Pekala recently noted 60 percent "is a whole lot better than zero percent."