Sometime this summer, if President Vladimir Putin can be believed, Russia moved some of its short-range nuclear weapons into Belarus, closer to Ukraine and onto NATO’s doorstep.

The declared deployment of the Russian weapons on the territory of its neighbor and loyal ally marks a new stage in the Kremlin’s nuclear saber-rattling over its invasion of Ukraine and another bid to discourage the West from increasing military support to Kyiv.

Neither Putin nor his Belarusian counterpart, Alexander Lukashenko, said how many were moved — only that Soviet-era facilities in the country were readied to accommodate them, and that Belarusian pilots and missile crews were trained to use them.

The U.S. and NATO haven’t confirmed the move. NATO Secretary-General Jens Stoltenberg denounced Moscow’s rhetoric as “dangerous and reckless,” but said earlier this month the alliance hasn’t seen any change in Russia’s nuclear posture.

Challenges in Tracking Nuclear Movements

While some experts doubt the claims by Putin and Lukashenko, others note that Western intelligence might be unable to monitor such movement.

Earlier this month, CNN quoted U.S. intelligence officials as saying they had no reason to doubt Putin’s claim about the delivery of the first batch of the weapons to Belarus and noted it could be challenging for the U.S. to track them.

The Tactical Nature of Nuclear Weapons

Unlike nuclear-tipped intercontinental ballistic missiles that can destroy entire cities, tactical nuclear weapons for use against troops on the battlefield can have a yield as small as about 1 kiloton. The U.S. bomb in Hiroshima in World War II was 15 kilotons.

The devices are compact: Used on bombs, missiles and artillery shells, they could be discreetly carried on a truck or plane. Aliaksandr Alesin, an independent Minsk-based military analyst, said the weapons use containers that emit no radiation and could have been flown into Belarus without Western intelligence seeing it.

“They easily fit in a regular Il-76 transport plane,” Alesin said. “There are dozens of flights a day, and it’s very difficult to track down that special flight. The Americans could fail to monitor it.”

Balarus’ Cold War-Era Nuclear Facilities

Belarus has 25 underground facilities built during the Cold War for nuclear-tipped intermediate-range missiles that can withstand missile attacks, Alesin said. Only five or six such depots could actually store tactical nuclear weapons, he added, but the military operates at all of them to fool Western intelligence.

Early in the war, Putin referenced his nuclear arsenal by vowing repeatedly to use “all means” necessary to protect Russia. He has toned down his statements recently, but a top lieutenant continues to dangle the prospect with terrifying ease.

Dmitry Medvedev, the deputy head of Russia’s Security Council who served as a placeholder president in 2008-12 because Putin was term-limited, unleashes near-daily threats that Moscow won’t hesitate to use nuclear weapons.

In a recent article, Medvedev said “the apocalypse isn’t just possible but quite likely,” and the only way to avoid it is to bow to Russian demands.

The world faces a confrontation “far worse than during the Cuban missile crisis because our enemies have decided to really defeat Russia, the largest nuclear power,” he wrote.

Many Western observers dismiss that as bluster.

Putin’s Nuclear Rhetoric Dialed Down Due to ‘Chinese Displeasure’

Putin seems to have dialed down his nuclear rhetoric after getting signals to do so from China, said Keir Giles, a Russia expert at Chatham House.

“The evident Chinese displeasure did have an effect and may have been accompanied by private messaging to Russia,” Giles told The Associated Press.

Moscow’s defense doctrine envisages a nuclear response to an atomic strike or even an attack with conventional weapons that “threaten the very existence of the Russian state.” That vague wording has led some Russian experts to urge the Kremlin to spell out those conditions in more detail and force the West to take the warnings more seriously.

Western Belief Putin Is Bluffing ‘Extremely Dangerous Delusion’

“The possibility of using nuclear weapons in the current conflict mustn’t be concealed,” said Dmitry Trenin, who headed the Moscow Carnegie Center for 14 years before joining Moscow’s state-funded Institute for World Economy and International Relations.

“The real, not theoretical, perspective of it should create stimuli for stopping the escalation of the war and eventually set the stage for a strategic balance in Europe that would be acceptable to us,” he wrote recently.

Western beliefs that Putin is bluffing about using nuclear weapons “is an extremely dangerous delusion,” Trenin said.