"Actions are taken to change the strategic balance of power. Of course, this cannot but cause concern in Russia," Peskov told reporters.
According to the spokesman, Russia is forced to respond to such actions, and the restraining effect of nuclear arms can hardly be disputed.
"The deterrent effect of nuclear weapons can hardly be disputed by anyone. The president explained in detail yesterday that it is not Russia that moves toward someone’s borders, but NATO military infrastructure that moves closer to Russia’s borders," he said.
Russia claimed previously that elements of US-led NATO’s ballistic missile shield deployed in Europe violated the Soviet-era Intermediate-Range Nuclear Forces (INF) Treaty it signed with Washington in 1987.
Last year, Moscow announced it was considering stationing nuclear-capable Iskander missiles in its westernmost exclave of Kaliningrad as a deterrent.
Russia has repeatedly expressed concerns over NATO's military buildup along its western borders, warning that the alliance's expansion undermines regional and global security.