President Obama’s announcement Thursday that he is revising U.S. antimissile plans in Europe triggered party-line responses from Capitol Hill, with Democrats strongly supportive and Republicans calling it “dangerous and short-sighted.”

Obama said he would no longer pursue the Bush administration’s plan to deploy interceptor missiles in Poland and a radar in the Czech Republic to intercept intercontinental missiles. Instead, he would develop more mobile antimissile systems on land and at sea that are designed to thwart, to begin with, shorter-range missiles, which he said are increasingly the threat being fielded by Iran. The system would ultimately provide a defense against intercontinental missiles, the White House said.

“This new approach will provide capability sooner, build on proven systems and offer greater defenses against the threat of missile attack than the 2007 European missile defense program,” Obama said.

Carl Levin , D-Mich., chairman of the Senate Armed Services Committee, said that Defense Secretary Robert M. Gates “assured us that both Poland and the Czech Republic are positive about this approach.”

Republicans responded that the move represented appeasement of Iran and Russia, which had opposed the system.

Senate Republican Whip Jon Kyl of Arizona, a longtime missile-defense advocate, issued a statement calling the proposal “dangerous and short-sighted.”

“Not only does this decision leave America vulnerable to the growing Iranian long-range missile threat, it also turns back the clock to the days of the Cold War, when Eastern Europe was considered the domain of Russia,” he added. “This will be a bitter disappointment, indeed, even a warning to the people of Eastern Europe.”