A U.S. lawmaker is warning the Obama administration against delaying the deployment of a missile defense system in Europe, saying it could weaken the support of key allies and undermine the program. His comments came during a Senate hearing, where a top Pentagon official said the United States is still undecided on how far to implement the program.

Deputy Defense Secretary William Lynn told the Senate Armed Services Committee the Obama administration has not made a decision on whether to move forward with deployment of a missile defense system in Europe.

He described the plan to install 10 two-stage interceptor missiles in Poland and a radar station in the Czech Republic as an option, and said the United States is also considering expanded missile defense cooperation with Russia. "We are looking at the alternatives in Europe, including the Polish-Czech option to defend against an Iranian missile threat. We are exploring the cooperation with the Russians as a potential additive to that kind of architecture. We haven't made a final decision on how to proceed there," he said.

The Obama administration is currently reviewing whether the missile defense system is technologically feasible and cost-effective, and whether there are other ways to counter or reduce the Iranian threat.

The Senate Judiciary Committee's newest ranking Republican, Sen. Jeff Sessions, R-Ala., 06 May 2009

But Senator Jeff Sessions, an Alabama Republican, urged the administration not to wait too long to decide on how to proceed with the anti-missile program. "If we can't make up our mind about it, it is not likely that the Poles and Czechs are going to be supportive of this system. I think it will undermine the whole process," he said.

The parliaments of the Czech Republic and Poland have not yet ratified the proposed installations on their territory. The deal also gives Poland a U.S. air defense system that includes a battery of Patriot missiles.

Russia strongly opposes the U.S. proposal to deploy a missile defense system in Central Europe and sees the plan as a threat to its security.

The United States says the anti-missile system is aimed at countering the threat posed by Iran and North Korea.

President Obama is expected to visit Moscow next month, where missile defense will likely be on the agenda.

Ahead of that trip, Defense Secretary Robert Gates said he sees a new willingness in Russia to help deal with the Iranian threat, raising the possibility of a deal.