For the first time since the mid-1990s, Moscow will deploy such weapons outside the country, Reuters writes.

Putin made the announcement at a time of rising tensions with the West over the war in Ukraine and with some Russian commentators speculating about possible nuclear strikes.

The United States - the world's other nuclear superpower - reacted cautiously.

A senior administration official noted that Russia and Belarus have been discussing such a deal for the past year and said there is no indication that Moscow plans to use its nuclear weapons.

Tactical nuclear weapons refer to those used to achieve specific successes on the battlefield, not those capable of destroying cities.

It is unclear how many such weapons Russia has, given that it is a territory still shrouded in Cold War secrecy.

Experts told Reuters the development was significant because until now Russia has prided itself on not deploying nuclear weapons beyond its borders, unlike the United States.

Putin told state television that Belarusian President Oleksandr Lukashenko had long voiced the issue of deploying tactical nuclear weapons in his country.

"There is nothing unusual here either: firstly, the United States has been doing this for decades. It has long placed its tactical nuclear weapons on the territory of its allied countries," he said.

"We agreed that we will do the same - without violating our obligations, I emphasize, without violating our international obligations regarding the non-proliferation of nuclear weapons."

A high-ranking official of the US administration noted that Moscow and Minsk have been talking about the transfer of nuclear weapons for some time.

"We have seen no reason to adjust our own strategic nuclear posture, nor any indication that Russia is preparing to use nuclear weapons.

We remain committed to the collective defense of the NATO alliance," the official said.

There was no immediate reaction from Lukashenka.

Putin did not specify when the weapons would be transferred to Belarus, which shares borders with three NATO members - Poland, Lithuania and Latvia.

"It's part of Putin's game to try to intimidate NATO because there's no military benefit to doing that in Belarus because Russia has so many of these weapons and forces inside Russia," said Hans Christensen, director of the Nuclear Information Project at the Federation of American Scientists.

The International Campaign to Abolish Nuclear Weapons condemned what it called an extremely dangerous escalation.

"In the context of the war in Ukraine, the probability of miscalculations or misinterpretation is extremely high. The joint use of nuclear weapons significantly worsens the situation and threatens catastrophic humanitarian consequences," the report says.

"This is a very important step," said Mykola Sokol, a senior researcher at the Vienna Center for Disarmament and Non-Proliferation.

"Russia has always been very proud of not having nuclear weapons outside its territory.

So now, yes, they're changing it, and it's a big change," he added.

After the collapse of the Soviet Union in 1991, nuclear weapons were deployed in four newly independent states: Russia, Ukraine, Belarus, and Kazakhstan.

In May 1992, the four powers agreed that all weapons should be based in Russia, and the transfer of warheads from Ukraine, Belarus, and Kazakhstan was completed in 1996.

We will remind that earlier

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"We will not transfer our tactical nuclear weapons to Belarus, but we will deploy them and train the military like the US in Europe," Putin said. 

Read also:

• Ukraine news

• War in Ukraine

• News of Ukraine: video

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