September 17, 2009 - The Obama administration plans to announce on Thursday that it will scrap former President George W. Bush's planned missile defense system in Poland and the Czech Republic and instead deploy a reconfigured system aimed more at intercepting shorter-range Iranian missiles, according to people familiar with the plans.

President Obama decided not to deploy a sophisticated radar system in the Czech Republic or 10 ground-based interceptors in Poland, as Mr. Bush had planned. Instead, the new system his administration is developing would deploy smaller SM-3 missiles, at first aboard ships and later probably either in southern Europe or Turkey, those familiar with the plans said.

The White House will announce the decision Thursday morning and Defense Secretary Robert M. Gates, who was first appointed by Mr. Bush, will then discuss it with reporters at 10:30 a.m. It amounts to one of the biggest national security reversals by the new administration, one that will upset Czech and Polish allies and possibly please Russia, which adamantly objected to the Bush plan. But Obama administration officials stressed that they are not abandoning missile defense, only redesigning it to meet the more immediate Iranian threat.

"The way forward enhances our homeland defense and protects our forces abroad as well as our European allies," said an administration official, who spoke on condition of anonymity to avoid upstaging the announcement by Mr. Gates. "Our review has been driven by an updated intelligence assessment of Iran's missile programs and new advances in our missile defense capabilities and technologies."

Administration officials said the Bush missile defense architecture was better designed to counter potential long-range missiles by Iran, but recent tests and intelligence have indicated that Tehran is moving more rapidly toward developing short- and medium-range missiles. Mr. Obama's advisers said their reconfigured system would be more aimed at that threat by stationing interceptor missiles closer to Iran.

The Obama administration has begun briefing allies on the decision, and the Czech prime minister confirmed that he received a phone call from Mr. Obama informing him of the plans.

"Today, shortly after midnight, American President Barack Obama contacted me by telephone to inform me that his administration is pulling out of plans to build a radar for the anti-missile defense system on the territory of the Czech Republic," Mr. Fischer said, adding that "Poland was informed in the same manner."

A Polish diplomat said early Thursday that Warsaw was waiting to hear, but added that "it is clear that the administration has other priorities."

In arranging a post-midnight call by Mr. Obama and quickly dispatching a top State Department official to Europe, the administration was scrambling to notify and assure the European allies as word of its decision was already leaking out in Washington. The Wall Street Journal reported Thursday that the administration would jettison the Bush architecture.

But it made for unfortunate timing, coming on the 70th anniversary of the Soviet invasion of Poland at the start of World War II, a date fraught with sensitivity for Poles who viewed the Bush missile defense system as a political security blanket against Russia.

Mr. Bush had developed a special relationship with Eastern Europe as relations between Washington and Moscow deteriorated. The proposal to deploy parts of the missile shield in Poland and the Czech Republic were justified on the grounds that they would protect Europe and the eastern coast of the United States against any possible missile attacks from Iran.

But the Polish and Czech governments saw the presence of American military personnel based permanently in their countries as a protection against Russia. Moscow strongly opposed the shield and claimed it was targeted against Russia and undermined national security. The United States repeatedly denied such claims.

Mr. Obama's advisers have said their changes to missile defense were motivated by the accelerating Iranian threat, not by Russian complaints. But the announcement comes just days before Mr. Obama is scheduled to meet privately with Russia's President Dmitri A. Medvedev in New York on the sidelines of next week's United Nations General Assembly session.

The administration maintains that the switch in the Bush plans does not indicate any diminishment of its relations with Poland and the Czech Republic. "The United States stands by its security commitments to its allies," said the official, who spoke on condition of anonymity.

Andrei Nesterenko, a spokesman for the Russian Foreign Ministry, said Thursday that the ministry was aware of the reports, but would await the announcement before formally commenting. But he said that if the anti-missile system was indeed being scrapped, it would be a "positive sign" for Russia.

The Obama review of missile defense was influenced in large part by evidence that Iran has made significant progress toward developing medium-range missiles that could threaten Europe, even as the prospects of an Iranian intercontinental ballistic missile that could reach the United States remain distant.

In May, Iran launched the Sejil-2, the first successful test of a solid-fuel missile. With an estimated range of around 1,200 miles, it could strike Israel or many parts of Europe. Unlike Iran's liquid-fuel missiles, a solid-fuel missile can be stored, moved around and fired on shorter notice, and thus is considered by military experts to be a greater threat.

The Obama team relied heavily on research by a Stanford University physicist, Dean Wilkering, who presented the government with research this year arguing that Poland and the Czech Republic were not the most effective places to station a missile defense system against the most likely Iranian threat. Instead, he said, more optimal places to station missiles and radar systems would be in Turkey or the Balkans.

"If you move the system down closer to the Middle East," it would "make more sense for the defense of Europe, Mr. Wilkering said in an interview.

Mr. Wilkering said the new administration did not want to simply abandon missile defense but orient it for a different threat than the Bush team saw. "The Obama administration is more interested in missile defense as a valuable instrument, a valuable aspect of our military posture than I would have thought," he said. Beyond moving the system from Eastern Europe, the Obama team concluded that the advantage of using the smaller SM-3 interceptors is that they have been proven effective and can be deployed sooner than the ground-based interceptors that the Bush team was still developing.

Mikhail Margelov, chairman of the foreign affairs committee in the upper house of Russia's parliament, said in an interview on Thursday that the decision would give a major boost to relations between the two countries. Mr. Margelov said it would in particular help negotiations when Mr. Obama meets with Russia's president, Dmitri A. Medvedev, at the United Nations next week.

"For Russia, it is a victory for common sense," Mr. Margelov said. "It another positive signal that we have received from Washington that makes the general climate very positive."

But Mr. Margelov expressed doubt that the decision would make Moscow more willing to support a push by the United States to increase sanctions against Iran over its nuclear activities. The Kremlin said last week that it would essentially block new sanctions, downplaying Western concerns that Iran had made progress in its bid for nuclear weapons.

Peter Baker reported from Washington and Nicholas Kulish from Berlin. Judy Dempsey contributed reporting from Berlin, and Clifford J. Levy from Moscow.

The New York Times