Russia will station tactical nuclear weapons in neighbouring Belarus, President Vladimir Putin said on Saturday, marking the first time since the mid-1990s that Moscow will have based such arms outside the country.

Putin made the announcement at a time of growing tensions with the West over the Ukraine war and as some Russian commentators speculate about possible nuclear strikes.

Putin told state television that Belarusian President Alexander Lukashenko had long raised the issue of stationing tactical nuclear weapons in his country, which borders Nato member Poland.

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

"We agreed that we will do the same – without violating our obligations, I emphasize, without violating our international obligations on the nonproliferation of nuclear weapons."

Putin did not specify when the weapons would be transferred to Belarus. "Tactical" nuclear weapons refer to those used for specific gains in the battlefield.

Russia will have completed the construction of a storage facility for tactical nuclear weapons in Belarus by July 1, Putin said, adding that Moscow would not actually be transferring control of the arms to Minsk.

The US State Department and the Pentagon did not immediately return messages seeking comment.

Russia has stationed 10 aircraft in Belarus capable of carrying tactical nuclear weapons, he said, adding that Moscow had already transferred to Belarus a number of Iskander tactical missile systems that can be used to launch nuclear weapons.

When the Soviet Union collapsed in 1991, nuclear weapons were deployed in the four newly-independent states of Russia, Ukraine, Belarus and Kazakhstan.

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