Russia will start deploying tactical nuclear weapons in Belarus after special storage facilities are made ready on July 7-8, President Vladimir Putin said on Friday, Moscow's first move of such warheads outside Russia since the fall of the Soviet Union.
Putin announced in March he had agreed to deploy such weapons in Belarus, pointing to US deployment of tactical nuclear weapons in a host of European countries over many decades.
"Everything is going according to plan," Putin told Belarusian President Alexander Lukashenko, discussing the planned nuclear deployment over a meal at the Russian leader's summer retreat in the Black Sea resort of Sochi.
"Preparation of the relevant facilities ends on July 7-8, and we will immediately begin activities related to the deployment of appropriate types of weapons on your territory," Putin said, according to a Kremlin transcript of his remarks.
Lukashenko said: "Thank you, Vladimir Vladimirovich."
More than 15 months into the biggest land war in Europe since World War Two, Putin says the United States and its Western allies are pumping arms into Ukraine as part of an expanding proxy war aimed at bringing Russia to its knees.
Putin, 70, casts the war as a battle for Russia's own survival in the face of what he says is an ever-expanding NATO. He has warned the West that Moscow will not back down.
Ukrainian President Volodymyr Zelenskiy says Ukraine will not rest until every last Russian soldier is ejected from his country, and wants it to join NATO as soon as possible.
Putin's nuclear move is being watched closely by both the United States and its NATO allies in Europe and by China, which has repeatedly cautioned against the use of nuclear weapons in the conflict.
The United States has criticized Putin's nuclear deployment but has said it has no intention of altering its position on strategic nuclear weapons and also that it has not seen any signs Russia was preparing to use a nuclear weapon.
The war in Ukraine has triggered what both Moscow and Washington says is the deepest crisis in relations since the depths of the Cold War, with major nuclear arms control treaties unravelling and both sides denouncing the other in public.
Putin's nuclear remarks have raised particular concern.
Last September, he warned the West he was not bluffing when he said Russia would use "all available means to protect Russia and our people".
It is still unclear where the Russian nuclear warheads - which will remain under Russian control - will be kept in Belarus.
Putin, who is the ultimate decision maker on any nuclear launch, said Iskander mobile short-range ballistic missiles, which can deliver nuclear warheads, had already been handed over to Belarus. Russian sources say the Iskander has a range of 500 km (310 miles).
Belarus said Su-25 aircraft had been adapted to carry the warheads. The Sukhoi-25 jet has a range of up to 1,000 km (620 miles), according to Russian sources.
If the weapons were launched from Belarus's main air base outside Minsk, those delivery vehicles could potentially reach almost all of eastern Europe - including a host of NATO members - as well as cities such as Berlin and Stockholm.
After the Soviet collapsed in 1991, the United States went to enormous efforts to return the Soviet nuclear weapons stationed in Belarus, Ukraine and Kazakhstan to Russia - which inherited the nuclear arsenal of the Soviet Union.
Until now, Russia has not announced any nuclear weapon deployments outside its borders.
Putin has repeatedly raised the issue of US B61 tactical nuclear warheads deployed at bases in Belgium, the Netherlands, Germany, Italy and Türkiye. Moscow is also unhappy about a reported upgrade of the B61, which was first tested in Nevada shortly after the Cuban Missile Crisis.