President Vladimir V. Putin of Russia said he would be able to position tactical nuclear weapons in Belarus by the summer, a move that threatened to increase tensions with the United States and Europe while his forces wage war in Ukraine.
The Russian leader has repeatedly raised the specter of using nuclear weapons since ordering the full-scale invasion of Ukraine last year. While U.S. officials have said they have seen no effort by Russia to move or employ its nuclear weapons and believe the risk of their use is low, worries have lingered.
Mr. Putin’s remarks about stationing weapons in Belarus — a prospect he first floated last year — could again be saber rattling. It would not necessarily change the battlefield calculus: Any targets that Moscow can strike from Belarus, which borders three NATO members, it can already strike from Russian territory.
American officials indicated that they did not immediately sense an escalation.
In an interview with state media released online on Saturday, Mr. Putin said that construction on a storage facility for tactical nuclear weapons in Belarus would be completed by July 1, according to the Tass news agency, though it was not immediately clear if or when nuclear weapons would be moved there.
Increasingly isolated from the West, Mr. Putin has been relying on allies such as Belarus — a country bordering Ukraine that was used as a staging ground for Moscow’s full-scale invasion. Mr. Putin claimed that President Aleksandr G. Lukashenko of Belarus had requested that Moscow station the weapons on his soil. There was no immediate comment from Mr. Lukashenko of Belarus.
Mr. Putin made the comments during a wide-ranging interview for a state television show dedicated to the Russian president called “Moscow. Kremlin. Putin,” which airs on Sunday nights.
In response to a question focused on Britain’s decision to send weapons containing depleted uranium to Ukraine, Mr. Putin condemned the British move and then said he was moving ahead with a plan, first revealed last year, to give Russia the ability to base nuclear weapons in Belarus.
But Mr. Putin cast his announcement as “nothing unusual,” saying the United States has long deployed its own nuclear weapons within the borders of its European allies.
“We are in principle doing all the same things that they have been doing for decades,” Mr. Putin said. “Without violating, I want to emphasize this, our international obligations on the nonproliferation of nuclear weapons,” he added.
His remarks added some details to what is known about Russia’s plan, including that Moscow would start training Belarusian crews to operate the weapons in April and that Russia had retrofitted 10 Belarusian warplanes to be able to carry the weapons.
But Mr. Putin was vague on when Russia would actually send Belarus the nuclear warheads themselves. Asked in a follow-up question by the interviewer, Pavel Zarubin, “when and under what conditions could the weapons themselves be handed over?,” Mr. Putin responded only by saying that Russia was replicating the American practice of “nuclear sharing” in which American nuclear weapons are based in allied countries like Germany.
Oleksiy Danilov, the head of the Ukrainian National Security and Defense Council, accused the Kremlin of taking Belarus “as a nuclear hostage.” Germany’s foreign ministry called Mr. Putin’s announcement “another attempt at nuclear intimidation.”
Late on Saturday, the Pentagon released an email statement saying: “We have seen reports of Russia’s announcement and will continue to monitor this situation.” It added: “We have not seen any reason to adjust our own strategic nuclear posture nor any indications Russia is preparing to use a nuclear weapon. We remain committed to the collective defense of the NATO alliance.”
Analysts said that behind Mr. Putin’s bluster, the immediate implications of his comments for nuclear security appeared to be minimal.
The Institute for the Study of War, a Washington-based research group, dismissed Mr. Putin’s announcement as an “information operation” with little risk of escalation.
“Putin is attempting to exploit Western fears of nuclear escalation,” it said, adding that the group “continues to assess that Putin is a risk-averse actor who repeatedly threatens to use nuclear weapons without any intention of following through in order to break Western resolve.”
Pavel Podvig, a longtime researcher of Russia’s nuclear forces at the United Nations Institute for Disarmament Research in Geneva, said he still considered it unlikely that Russia would actually move nuclear warheads into Belarus, despite Mr. Putin’s latest comments.
Russian nuclear storage sites are so complex, Mr. Podvig said, that he doubted that a facility in Belarus could be ready to receive them by July.
“It’s not a positive development, of course, but as long as the weapons are in storage the threat is not immediate,” Mr. Podvig said. “Yes, theoretically, Russia can reach more targets from Belarus, but the change is marginal.”
Russia has as many as 2,000 tactical nuclear weapons, which have a lower yield than the strategic kind that can traverse entire continents. A tactical nuclear weapon has never been used in combat, but one could be deployed in a number of ways, including by missile or artillery shell.
Christopher F. Schuetze contributed reporting.