A group of prominent scientists who have been critical of missile defense plans told lawmakers Wednesday that a system being built by the United States cannot protect the country. They also questioned whether the US Defense Department has misled the public and European allies about the system's capabilities. "The (global missile defense) program offers no prospect of defending the United States from a real-world missile attack and undermines efforts to eliminate the real nuclear threats to the United States," Lisbeth Gronlund, a senior scientist at the Union of Concerned Scientists, told lawmakers at a House of Representatives oversight hearing on the missile defense program, according to prepared testimony. Gronlund's group has long expressed skepticism about missile defense. The hearing was called by the panel's chairman, Democratic Rep. John Tierney, who has sought to step up oversight of the missile defense program since the Democrats took control of the House last year. Missile defense traditionally has drawn more support from Republicans. Tierney said the testimony from the witnesses raises questions about current missile defense spending levels. He pointed to congressional projections of $213-$277 billion for the program between now and 2025. "We need to all ask ourselves, whether you're a conservative Republican or a liberal Democrat: "Are we wisely spending the taxpayer's money here," Tierney said in his opening remarks. The Bush administration has sought to deploy a working missile defense system while it is testing the parts, arguing that there is an urgent threat from hostile countries developing intercontinental missiles, such as Iran and North Korea. The program has been a major source of rising tension with Russia, which opposes US plans to build part of the system in Poland and the Czech Republic. Jeff Kueter, the president of the George C. Marshall Institute in Washington and a Republican witness at the hearing told the panel the program is making progress and already has limited abilities to counter ballistic missiles. "Even in their current form, the elements of the US missile defense system offer options heretofore unavailable," he said. "With further research, development and testing, the accuracies and capabilities of these systems will only improve." But the other witnesses said that recent tests of the system, to take out long range missiles in mid-flight with ground-based interceptors, have been unrealistic. They said the defenses can be easily overcome by countermeasures, such as decoys deployed along with warheads on the missiles. One of the witnesses, Philip Coyle, a former assistant secretary of defense in the administration of President Bill Clinton in charge of testing weapons systems, called decoys the Achilles heel of the US system, including the interceptors planned for Poland and the Czech Republic. A spokesman for the Missile Defense Agency, Rick Lehner, says the agency's tests are getting more rigorous over time and will add more challenging countermeasures. "We are injecting true operational realism into the tests," he said in an e-mail. "It's hard to believe that the critics ... are still clinging to the notion that we cannot, and should not, have the means to protect Americans from a ballistic missile attack." The critics contend that their worry is that the highly expensive system will never be able to decipher decoys from warheads. "The primary responsibility, that of protecting the United States against attack by nuclear weapons or biological weapons, is a failure and will remain so for the foreseeable future, so long as MDA attempts to carry it out by midcourse intercept," said Richard Garwin, a renowned physicist credited with playing a major role in the design of the first hydrogen bomb.