While First Deputy Prime Minister Sergei Ivanov accused the United States of aggressive military activity in Europe, his comments signaled more flexibility than the initial Russian reaction to the proposals the U.S. submitted in writing last week.
He spoke hours before expected discussions on the matter - a major irritant in Russia-U.S. relations - between Russian Foreign Minister Sergey Lavrov and U.S. Secretary of State Condoleezza Rice before Middle East peace talks in the United States.
"We are ready for dialogue, but at the same time we are of course guided by our national interests, and if our partner has new military capabilities next to our borders ... we probably have to think about it," Ivanov told Russian News Service radio.
Russia has sharply opposed U.S. plans to deploy missile defense installations in Poland and the Czech Republic. The United States says the system would counter a potential Iranian threat, but Moscow says it believes the real aim is to weaken Russia's nuclear deterrent.
Earlier this year, President Vladimir Putin offered an alternative involving joint use of a Russian-operated radar station in Azerbaijan, but has cited the U.S. plans as a factor in his decision to suspend Moscow's participation in the Conventional Forces in Europe treaty, which limits regional military deployments.
U.S. President George W. Bush's administration welcomed Putin's offer but pushed ahead with its plans for Eastern Europe, while continuing talks with Russia on missile defense cooperation.
The initial Russian reaction to the formal proposals Washington sent last week was chilly.
A top lawmaker said the proposals fell short of "real cooperation," and Russian news agencies quoted an unidentified Foreign Ministry official as suggesting the United States had gone back on its word since talks last month between Rice and Lavrov and the two nations' defense chiefs.
In an interview published Monday, Lavrov said Russia was "as before, ready for serious cooperation on missile defense with the United States and other interested countries." But he reiterated Russia's doubts about an Iranian threat, and hinted the formal U.S. proposals were not enough to dispel the disagreements.
"We'll see how the U.S. approaches to this issue will develop further," Lavrov told the weekly Itogi.