Defense Minister Sergei Shoigu accused the United States on Thursday of working on military "scenarios" near Russia's borders that he said were a source of grave concern.
Interfax news agency quoted Shoigu as expressing surprise at a speech on Wednesday in which U.S. Defense Secretary Chuck Hagel said U.S. armed forces "must deal with a revisionist Russia — with its modern and capable Army — on NATO's doorstep".
"Chuck Hagel's thesis on the necessity for the American army to 'deal' with 'modern and capable' Russian armed forces on NATO's doorstep is of grave concern," Shoigu said, according to Interfax.
"This testifies to the fact that the Pentagon is working on scenarios for operations at the borders of our country."
Shoigu did not say what he thought the U.S. military was planning.
Washington has been open about its deployment of additional troops to Central and Eastern Europe, including Poland and the Baltic states, on manoeuvers intended to signal its commitment to nervous NATO allies.
Since the collapse of Communism, NATO has expanded eastward to take in three former Soviet republics and a clutch of ex-communist states once dominated by Moscow, in what Russia views as a serious threat.
Shoigu said an "impartial dialogue" was needed with Russia's Western partners on all aspects of relations, instead of "pumping up tension."
His comments marked Moscow's second forceful intervention in two days on the topic of relations with the United States.
In an interview published on Wednesday, President Vladimir Putin warned Washington that a "spat between major nuclear powers" over the Ukraine crisis could threaten global stability, and said Russia would not be "blackmailed" by Western sanctions.