President-elect Barak Obama could order a review of US missile shield plans after he takes office to see how the system is evolving and whether it is cost effective, a senior US official said on Monday.
However the official, speaking to AFP on condition of anonymity, underlined that Obama, who will be sworn in on Tuesday, had shown no signs that he would drop the project which has deeply angered Russia.
"I would not at all be surprised for a new administration to want to review: Where do we stand in this programme now? What's the level of technological development? What are the costs?" the official said.
But he added: "There's nothing there at this point that would cause you to say that there's a political disagreement or a walking away from missile defence."
Obama has yet to say whether he intends to continue with the project developed under the outgoing administration of President George W Bush, and this has helped feed speculation that it could be wound down.
The United States is in the process of finalising an agreement to base missile interceptors and radar in Poland and the Czech Republic to counter any future threat from "rogue states" like Iran.
But Russia fears that the missile shield extension is a threat to its own missile capabilities and has vowed to counter the move.
US arms negotiator John Rood said last month that Moscow had hardened its stance toward the missile plans in an apparent bid to "test the mettle" of Obama.
The senior US official underscored that the shield was not aimed at Russia.
"It will be important to continue to convey that to Russia, that this is about threats emerging in the south and east, not from Russia," he said.