MOSCOW — Russian President Vladimir Putin announced plans on Saturday to station tactical nuclear weapons in neighboring Belarus, a warning to the West as it steps up military support for Ukraine.

Putin said the move was triggered by Britain’s decision this past week to provide Ukraine with armor-piercing rounds containing depleted uranium.

Tactical nuclear weapons are intended for use on the battlefield and have a short range and a low yield compared with much more powerful nuclear warheads fitted to long-range missiles. Russia plans to maintain control over those it sends to Belarus, and construction of storage facilities for them will be completed by July 1, Putin said.

He didn’t say how many nuclear weapons Russia would keep in Belarus. The U.S. government believes Russia has about 2,000 tactical nuclear weapons, which include bombs that can be carried by tactical aircraft, warheads for short-range missiles and artillery rounds.

Putin argued that by deploying its tactical nuclear weapons in Belarus, Russia was following the lead of the United States, noting that the U.S. has nuclear weapons based in Belgium, Germany, Italy, the Netherlands and Turkey.

“We are doing what they have been doing for decades, stationing them in certain allied countries, preparing the launch platforms and training their crews,” Putin said, speaking in an interview on state television that aired Saturday night. “We are going to do the same thing.”

Russia has stored its tactical nuclear weapons at dedicated depots on its territory, and moving part of the arsenal to a storage facility in Belarus would up the ante in the Ukrainian conflict by placing them closer to the Russian aircraft and missiles already stationed there.

Some hawkish commentators in Russia long have urged the Kremlin to put the tactical nuclear weapons close to the weapons to send a signal to the West about the readiness to use them.

The U.S. said it would “monitor the implications” of Putin’s announcement.

“We have not seen any reason to adjust our own strategic nuclear posture nor any indications Russia is preparing to use a nuclear weapon,” National Security Council spokesperson Adrienne Watson said. “We remain committed to the collective defense of the NATO alliance.”

Belarus, Kazakhstan and Ukraine had Soviet nuclear weapons stationed on their territory but handed them over to Russia after the 1991 collapse of the Soviet Union.

Putin said Belarusian President Alexander Lukashenko has long asked to have nuclear weapons in his country again as a counter to NATO. Belarus shares borders with three NATO members — Latvia, Lithuania and Poland — and Russia used its territory as a staging ground to send troops into neighboring Ukraine on Feb. 24, 2022.

Putin noted that Russia helped modernize Belarusian military aircraft last year to make them capable of carrying nuclear warheads. He said 10 such planes were ready to go. He said nuclear weapons also could be launched by the Iskander short-range missiles that Russia provided to Belarus last year.

Belarusian opposition leader Sviatlana Tsikhanouskaya, who is living in exile, said the agreement to transfer the tactical nuclear weapons to Belarus “underlines the threat to regional security” from Lukashenko’s regime.

“Europe won’t be safe until Belarus dictator is removed & brought before tribunal to face justice for crimes against our country & Ukraine,” Tsikhanouskaya wrote in English on Twitter.

Lukashenko’s support of the war has drawn international criticism and sanctions. But he has publicly stood by Russia, which has pumped billions of dollars into shoring up his Soviet-style, state-controlled economy with cheap energy and loans.

Putin had initially objected to the depleted uranium rounds that Britain promised to ship to Ukraine by making the false claim that they have nuclear components.

He subsequently toned down his language, but insisted Saturday that the ammunition posed an additional danger to both troops and civilians in Ukraine by leaving a radioactive trace and contaminating agricultural land.

“Those weapons are harmful not just for combatants, but also for the people living in those territories and for the environment,” he said.

Putin added that Russia has vast stockpiles of similar ammunition but so far has refrained from using it.

Depleted uranium is a byproduct of the uranium enrichment process needed to create nuclear weapons. The rounds can’t generate a nuclear reaction but they do emit low levels of radiation. The U.N. nuclear watchdog has warned of the possible dangers of exposure.

Such rounds were developed by the U.S. during the Cold War to destroy Soviet tanks, including the same T-72 tanks that Ukraine now faces in its push to break through a stalemate in the east.