Romania's supreme defence council has approved a US proposal to place anti-ballistic missile interceptors in the country as part of Washington's revamped missile shield.
President Traian Basescu announced on Thursday that NATO-member Romania would host "ground capabilities to intercept missiles" that would "increase its national security" when they become operational in 2015.
Mr Basescu reiterated the White House line that the interceptor missiles are not directed against Moscow, saying: "Romania will not host a system directed against Russia, but against other threats."
US State Department spokesman Philip Crowley confirmed the plan, which has yet to be approved by Romanian MPs.
"Romania has agreed to host a Standard Missile 3 interceptor as part of the administration's new missile defence plan to protect US forward-deployed troops and our NATO allies against current and emerging ballistic missile threats from Iran."
Mr Crowley also tried to assuage Russian concerns, saying: "As we have made clear over and over again, this is not a capability that is directed at Russia."
But Moscow insists that "the only good missile defence is missile defence together with Russia."
Russian Foreign Ministry spokesman Andrei Nesterenko said:"Withdrawal of American tactical weapons from Europe back to the United States would be welcome.
"It should be accompanied by complete and irreversible demolition of the entire infrastructures supporting the deployment of such weapons in Europe," he said.
In September, US President Barack Obama responded to pressure from Moscow by ditching a costly Bush-era plan to install a long-range shield of 10 missile interceptors in Poland, linked to a radar base in the Czech Republic.
The following month, US Vice-President Joseph Biden visited Romania as part of his tour of central Europe where he presented a revamped US missile shield plan.
Romania's Supreme Defence Council made its decision on Thursday, the same day that Mr Basescu met US Under Secretary of State for Arms Control Ellen Tauscher.
The Romanian premier declared that bilateral negotiations with the US would begin soon.
This week, the Obama administration asked for £5.4 billion for the
missile shield, an increase of more than £500 million on the previous
year.