EU foreign policy chief Josep Borrell on Sunday urged Belarus not to host Russian nuclear weapons, saying it could face further sanctions if it did.
"Belarus hosting Russian nuclear weapons would mean an irresponsible escalation and threat to European security. Belarus can still stop it, it is their choice. The EU stands ready to respond with further sanctions," Borrell said in a tweet.
He added that Brussels was ready to impose new sanctions on Belarus if Minsk were to host Russian nuclear weapons.
Russian President Vladimir Putin announced on Saturday that Moscow plans to station tactical nuclear weapons in Belarus.
Ukraine on Sunday called for an emergency meeting of the United Nation's Security Council over Russia's announcement that it would station tactical nuclear weapons in Belarus.
"Ukraine expects effective actions to counteract the Kremlin's nuclear blackmail from the United Kingdom, China, the United States and France... We demand that an extraordinary meeting of the UN Security Council be immediately convened for this purpose," the Ukrainian foreign ministry said.
Kyiv on Sunday said Russia was holding Minsk as a "nuclear hostage" after Russian President Vladimir Putin announced the deployment of tactical nuclear weapons to ally Belarus.
"The Kremlin took Belarus as a nuclear hostage," the secretary of Ukraine's National Security and Defence Council, Oleksiy Danilov, wrote on Twitter, adding that the move was "a step towards the internal destabilization of the country".
Putin has repeatedly issued thinly veiled threats he could use nuclear weapons in Ukraine, reviving Cold War-era fears.
He also said he would deploy depleted uranium ammunition if Kyiv received such munitions from the West following a British suggestion that it could supply Ukraine.
"There is nothing unusual here either: the United States has been doing this for decades. They have long placed their tactical nuclear weapons on the territory of their allies," Putin said.
Putin said he spoke to Belarusian leader Alexander Lukashenko and said "we agreed that we to do the same."
On the question of how Moscow would respond if the West supplied Ukraine with depleted uranium shells, following a suggestion by Britain it could supply Kyiv with the munitions, Putin said Russia had vast quantities of the weaponry.
"Russia of course has what it needs to answer. Without exaggeration, we have hundreds of thousands of such shells. We have not used them yet," Putin added in an interview on Russian television.
The International Campaign to Abolish Nuclear Weapons (ICAN) has warned nuclear threats were creating a dangerous sense of uncertainty around their possible use.
The longer Russia's operation in Ukraine grinds on, the greater the nuclear strike risk, ICAN warned last month ahead of the offensive's first anniversary.
Putin announced last month that Moscow would suspend its participation in New START, the last remaining arms control treaty between the world's two main nuclear powers Russia and the United States.
NATO chief Jens Stoltenberg slammed Russia for suspending the nuclear weapons limitation treaty with the US, saying it marked the end of Europe's post-Cold War arms control architecture.
The announcement came after Moscow last August suspended US inspections of its military sites under New START.
'Dirty bomb' claims
Putin previously said at a Kremlin meeting that "such a threat is rising" on the use of nuclear weapons but has been evasive on Russia's policy.
US officials have voiced fears that Russia could use nuclear weapons if it feels routed on the battlefield and could plant a fictitious story to justify its actions.
Russia has already spoken of supposed Ukrainian attempts to detonate a "dirty bomb," drawing strong denials from Ukraine and a sharp rebuke from the United States, which had rare direct communication with Moscow to warn against nuclear use.
Neither the United States nor Russia -- by far the largest nuclear weapons powers -- officially has a policy of no first use of the ultra-destructive arms.
A recent US posture review by President Joe Biden concluded only that nuclear weapons should only be used in "extreme circumstances."
(FRANCE 24 with AFP)