The most controversial part of the U.S. missile defense system involves putting a sophisticated tracking radar in the Czech Republic and anti-missile missiles in Poland to intercept any Iranian launch aimed at Europe.
While some missile defense technologies have had numerous successful tests, including sea-based interceptors and warheads designed to destroy long-range missiles over the ocean, the medium-range system planned for Europe has not been tested and is the subject of much criticism.
At the same time, Russia claims the Poland-based missiles would threatened its defenses. U.S. officials deny that. But Russia has made the issue a central obstacle to the kind of improvement in relations the Obama administration says it wants.
The Chairman of the Senate Armed Services Committee, Carl Levin, indicated Monday he believes the European part of the missile defense system should be dropped in favor of a new approach that would not antagonize Moscow.
"It appears that the door to cooperation between the United States and Russia is gradually opening, and missile defense could become a tool for positive change rather than an impediment to better relations," he said.
Levin said although cooperation with Russia on missile defense seems unlikely in the current environment, it is "worth a try" because it could be what he called "a geopolitical game changer."
"U.S.-Russian cooperation on missile defense against Iranian missiles, even if we were just to begin serious discussions on the subject, would send a powerful signal to Iran," he said. "Iran would face in a dramatic way a growing unity against her pursuit of dangerous nuclear technology."
The senator says the downside of such an approach would be minimal, although some experts express concern about the United States backing out of plans it has pressed Poland and the Czech Republic to accept. Experts also point out that the Bush administration tried to work with Russia on missile defense, but concluded that it was not a realistic possibility.
At the same conference for missile defense officials and contractors, another member of Congress pointed out a different shortcoming of the European missile defense plan.
Representative Ellen Tauscher said that even if the system can work, it would not protect U.S. allies in the Middle East or U.S. troops deployed there against Iran's large arsenal of shorter-range missiles.
"These systems are currently capable of targeting U.S. forces and our allies throughout the region," she said. "And guess what? The proposed interceptor in Poland would have little, if any, capability to counter the existing threat from Iran's short- and medium-range ballistic missiles."
Tauscher, who announced last week she will leave Congress to take the top arms control post at the State Department, also chided the Pentagon for not yet proving the system planned for Europe works.
"The world is a very dangerous place. Non-state actors and rogue nations are working to develop missile technology to do harm to America, American interests and our forward-deployed troops," she said. "That is why we need missile defense systems that work."
Speaking on a computer link from his headquarters in Colorado, the head of U.S. Northern Command, Air Force General Gene Renuart, who is responsible for defending the United States, told the meeting he has confidence in the missile defense system, but acknowledged there is still much work to do.
"I am a strong supporter of the system and the program and the current regimen on," he said. "However, we do have to continue to stay focused on those key elements of both operational test and operational employment."
The Obama administration has not said what it will do with the controversial European missile defense system, but it has said it wants to "reset" U.S. relations with Russia. The issues are under review, and the results are expected soon.