President Barack Obama has decided to abandon Bush administration plans for a large-scale missile defence system in Poland and the Czech Republic in a move that should ease tensions with Russia.
In a brief announcement today, Mr Obama said: "The best way to responsibly advance our security and the security of our allies is to deploy a missile defence system that best responds to the threats that we face and that utilises technology that is both proven and cost effective.
"To put it simply, our new missile defense architecture in Europe will provide stronger, smarter, and swifter defenses of American forces and America's allies," Mr Obama said.
"It is more comprehensive than the previous program; it deploys capabilities that are proven and cost-effective; and it sustains and builds upon our commitment to protect the US homeland against long-range ballistic missile threats; and it ensures and enhances the protection of all our Nato allies."
The president said he had spoken to the prime ministers of the Czech Republic and Poland about the decision "and reaffirmed our deep and close ties".
"We've also repeatedly made clear to Russia that its concerns about our previous missile defense programs were entirely unfounded. Our clear and consistent focus has been the threat posed by Iran's ballistic missile program, and that continues to be our focus and the basis of the program that we're announcing today," Mr Obama said.
"In confronting that threat, we welcome Russians' co-operation to bring its missile defense capabilities into a broader defense of our common strategic interests, even as we continue to - we continue our shared efforts to end Iran's illicit nuclear program."
Citing US intelligence that Iran was less focused on developing an effective intercontinental ballistic missile programme, the Obama administration plans to shift to a different kind of defence officials said would be better able to defend against short- and medium-range missiles.
Russian President Dmitry Medvedev welcomed the US move. In a statement, he said: "We value the US president's responsible approach to implementing our agreements. I'm ready to continue the dialogue."
A White House spokesman today said missile-defence changes did not include a quid pro quo with Russia.
Officials in Poland, where Washington planned to base interceptor missiles, and the Czech Republic, which was to host a radar system, said they had been informed of the change.
Defence Secretary Robert Gates said today the United States would deploy Aegis ships equipped with interceptors to defend European allies and US forces against more immediate threats as part of a revamped missile shield programme.
Mr Gates said land-based defence systems would be fielded in a second phase starting in about 2015.
Mr Obama has acknowledged Russian sensitivities over former president George W. Bush's plans to build the missile-defence sites, which Washington insisted would guard against any long-range missile threat from Iran.
Former secretary of state Condoleezza Rice formally signed the deal with Poland a year ago despite Russia objections that the plans were a threat to its security.
Pentagon spokesman Geoff Morrell said the planned missile defence shield in Poland and the Czech Republic had been based on the concern that Iran was determined to develop long-range intercontinental missile capability.
He said recent intelligence showed the Iranians were much more focused on developing short- and medium-range missiles.
"We are adjusting our system to make sure our forces and our allies are protected from that changing and growing threat. Just as the threat has developed, so too has our technology. We believe we have a more flexible, capable system to deploy to protect our forces and friends in Europe," Mr Morrell said.
"This improvement to the system has nothing to do with Russia and everything to do with Iran," he added.
Iran denies Western charges that it is seeking to develop nuclear weapons, and says its missiles are for defence.
Iran and six world powers - the United States, Russia, China, Britain, France and Germany - are due to start wide-ranging talks on October 1st.
The Wall Street Journalsaid the administration "was expected to leave open the option of restarting the Polish and Czech system if Iran makes advances in its long-range missiles in the future".
Reuters