The Iskander-M contains two guided missiles with a range of up to 300 miles and can carry conventional or nuclear warheads.
Putin said that Belarusian President Alexander Lukashenko had requested the deployment for a long time. There was no immediate reaction from Lukashenko.
After the collapse of the Soviet Union in 1991, Belarus, Ukraine and Kazakhstan had nuclear weapons stationed on their territory, so this could be the first time since then that Russia has based such weapons outside their country.
American reaction to Putin's announcement was muted. The National Security Council spokesperson Adrienne Watson told NBC News late Saturday that the U.S. had not seen any reason to change our strategic nuclear posture or indications that Russia is preparing to use a nuclear weapon. But Oleksiy Danilov, secretary of Ukraine's National Security and Defense Council, tweeted that the Kremlin took Belarus as a nuclear weapon. The Belarusian army did not fight in Ukraine, but the country has close relationship with Russia, and Minsk allowed Moscow to send troops into Ukraine last year. The two nations have increased joint military training. Russia is Belarus' largest political and economic partner.
NATO said the organization was closely monitoring the situation, despite Russia calling its nuclear rhetoric dangerous and irresponsible. We haven't seen any changes in Russia's nuclear posture that would lead us to adjust our own, it said. We are committed to protect and defend all NATO allies. NATO stated that Moscow had broken its arms control commitments, most recently suspending its participation in the New START Treaty, a key nuclear arms control treaty between the US and Russia, the world's two largest nuclear powers.
Hamish de Bretton-Gordon, a former commanding officer of Britain and NATO's joint chemical, biological, radiological and nuclear regiment, called the plan a strategic error and another sign of desperation coming from the Kremlin after 13 months of war in Ukraine and few victories to show for it.
He said that Putin is clutching at straws, as Russian forces have been hammered around Bakhmut, where brutal battles for control of the eastern city have raged for months, with neither side gaining much ground.
He said that moving such weapons closer to NATO nations like Germany, Poland and Lithuania was likely to haveten Western weapons delivered to Ukraine. Germany, which has previously been cautious about providing military aid to Ukraine, might be encouraged by the potential threat of closer nuclear weapons, he said.