The Kremlin on Monday said Western criticism would not change plans announced by President Vladimir Putin to deploy tactical nuclear weapons in neighbouring Belarus.
The West condemned Putin's weekend announcement on placing the weapons in EU and NATO-bordering Belarus, triggering calls for new sanctions on Moscow.
Ukraine said it was seeking an emergency meeting of the UN Security Council over the move.
"Such a reaction of course cannot influence Russian plans," Kremlin spokesman Dmitry Peskov said.
Speaking during a televised interview on Saturday, Putin said Moscow would station the tactical nuclear weapons "without violating our international agreements on nuclear non-proliferation".
He said this was "nothing unusual".
"The United States has been doing this for decades. They have long placed their tactical nuclear weapons on the territory of their allies," Putin said.
The Russian leader said he spoke to his Belarusian ally Alexander Lukashenko and that they had "agreed to do the same".
Putin's announcement came over a year into his grinding offensive in Ukraine. An earlier report adds from Brussels: The NATO alliance on Sunday condemned Russia's announcement that it would deploy tactical nuclear weapons to Belarus as "dangerous and irresponsible".
But spokeswoman Oana Lungescu said the western allies had not yet "seen any changes in Russia's nuclear posture that would lead us to adjust our own."
Ukraine has sought an emergency meeting of the UN Security Council to discuss Moscow's plan, announced Saturday, to deploy tactical warheads to neighbouring Belarus.
Russia launched a full-scale invasion of Ukraine last year, with some of its troops crossing the border through its ally Belarus, and Kyiv sees the move as "nuclear blackmail".
President Vladimir Putin counters by comparing the move to the United States basing some of its nuclear arsenal on the territory of its European allies.
But NATO joined Germany in dismissing this analogy.
"Russia's nuclear rhetoric is dangerous and irresponsible. NATO is vigilant, and we are closely monitoring the situation," Lungescu said.
"Russia's reference to NATO's nuclear sharing is totally misleading. NATO allies act with full respect of their international commitments,"
"Russia has consistently broken its arms control commitments, most recently suspending its participation in the New START Treaty," she said.
Last month Putin said that Moscow would suspend participation in the New START treaty, the last nuclear arms control pact between Russia and the United States.
"Russia must return to compliance and act in good faith," the NATO spokesman said.