The head of the United States' missile defense program sought Wednesday to bolster Washington's argument for anti-missile sites in Europe by warning that Iran has sped up development of long-range missiles. Facing tough opposition from Russia and increasing skepticism from Poland, where the US wants to place part of the system, the American officials are trying to convince Europeans that program is crucial to guarding against an emerging threat from Iran. "They are developing missiles today in an accelerated pace," Lt. Gen. Henry Obering said in remarks at the Foreign Ministry in the Czech Republic, where Washington wants to install a radar facility as part of the system. Obering, director of the Pentagon's Missile Defense Agency, said Iran was the third most active country in flight testing missiles last year, behind Russia and China. "They're developing ranges of missiles that go far beyond anything they would need in a regional fight, for example, with Israel," Obering said. "Why are they developing missiles today that ... will be possible to reach Europe in few years?" he asked. The US is in talks with the Czech government about plans to place a missile tracking radar system at a base in a military area near Prague. Washington also wants to place 10 interceptor missiles in Poland as part of the defense shield, which it says is needed to protect its European allies against a possible missile strike from Iran. Iran recently announced it manufactured a new missile - the Ashoura - with a range of 2,000 kilometers (1,200 miles) that was capable of reaching Israel and US bases across the Middle East. "They also made statements that once you reached that range, getting beyond that is fairly easy," Obering said. "Currently, there's no protection in Europe against the intermediate-range or long-range weapons," he warned. The Czech government has been receptive to the proposal, but the US faces strong opposition from Russia, which argues that an installation so close to its border threatens its security. Months of negotiations with Moscow and America's insistence that the system is not aimed at Russia have failed to ease those worries. In another complication for Washington, Poland's newly elected government has responded much more cautiously to the plans than its predecessor. Poland's defense minister visited Washington Tuesday for discussions on a demand for US security aid in exchange for agreeing to have the anti-missile site on its territory. The defense chief, Bogdan Klich, said US officials appeared receptive to the request for aid in upgrading the country's air defense systems. Poland's new leaders are concerned about the potential security risks in agreeing to allow the interceptors on its territory and have sought consultations on the matter with NATO. Russia has warned that its own missiles could target the site in Poland. Obering spoke at the start of a two-day meeting to discuss the possibilities for Czech companies and researchers to participate in building the system. Foreign Minister Karel Schwarzenberg said Wednesday that Czech and US officials could sign a framework agreement in the next few months that "should open new possibilities for mutual partnership on missile defense, including research, development, design, testing, deployment, and support of an integrated ballistic missile defense system." Obering said the US has made "tremendous progress" in winning over NATO allies for the missile defense shield but acknowledged "frankly, less progress with the Russians."