According to Russian state media, President Putin stated that the move would not violate nuclear non-proliferation treaties and compared it to the US stationing its weapons in Europe.
Moscow would not be transferring control of its arms to Minsk, he added.
The US said it did not believe Russia was preparing to use nuclear weapons after the announcement.
“We have not seen any reason to adjust our own strategic nuclear posture,” the US Defense Department said in a statement.
“We remain committed to the collective defence of the Nato alliance.”
Belarus borders Ukraine, as well as Nato members Poland, Lithuania, and Latvia.
Moscow will be storing nuclear weapons outside the country for the first time since the mid-1990s.
Following the disintegration of the Soviet Union in 1991, weapons were transferred to four newly independent states: Russia, Ukraine, Belarus, and Kazakhstan, with the transfer of all warheads to Russia completed in 1996.
Belarus is a staunch Kremlin ally and supporter of the Ukrainian invasion.
On Saturday, President Putin told Russian state television that Belarusian President Alexander Lukashenko had long raised the issue of tactical nuclear weapons stationing in Belarus.
“There is nothing unusual here either,” he said. “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.”
Russia will start training crews to operate the weapons from next week. The construction of a storage facility for tactical nuclear weapons in Belarus will be completed by 1 July, President Putin added.
A small number of Iskander tactical missile systems, which can be used to launch nuclear weapons, have already been transferred to Belarus, President Putin said.
He did not specify when the weapons themselves would be sent.
The announcement to station weapons in Belarus comes only days after Chinese President Xi Jinping’s visit to Moscow, during which Russia and China issued a joint statement saying “all nuclear powers must not deploy their nuclear weapons beyond their national territories, and they must withdraw all nuclear weapons deployed abroad.”
On Sunday, a top security adviser to Ukrainian President Volodymyr Zelensky said that Russia’s plans are a “step towards internal destabilisation” of Belarus and predicted anti-Russian sentiment in the country would grow. “The Kremlin took Belarus as a nuclear hostage,” Oleksiy Danilov wrote on Twitter.
And exiled Belarusian opposition leader Svetlana Tikhanovskaya said that Russia’s deployment of tactical nuclear weapons “grossly contradicts the will of the Belarusian people”.