Kremlin spokesman Dmitry Peskov's comments, reported Wednesday by Russian news agencies, came in response to a report by Germany's ZDF television.
The report said that preparation is underway by the US to station B61-12 nuclear bombs at Buechel Air Base in Germany.
ZDF said its information was based on examination of US federal budget reports. The claim couldn't immediately be confirmed.
The B61-12 is an upgraded version of weapons that have been in the US arsenal for decades, developed under what is called the Life Extension Program.
The National Nuclear Safety Administration said in July that the upgrade included a new tail-kit assembly and would improve the bomb's reliability and security.
Peskov said "unfortunately, if this step is implemented... it may disrupt the strategic balance in Europe and therefore will clearly make Russia take corresponding countermeasures to re-establish the balance."
He didn't specify what those measures might be.
The US military responded that the weapons could not be considered as new. Pentagon spokesman, Army Lt. Colonel Joe Sowers, said "life-extended weapons are not 'new' weapons. LEPs will not provide new capabilities or meet new military requirements."