A day after the Russian president’s comment, his US counterpart hit back: “If he has no intention, why does he keep talking about it?”
Putin roundly attacked the West in a rambling speech on Thursday, playing down the chance of nuclear conflict and insisting Russia had not threatened to use such weapons.
He said he had only responded about the issue to nuclear “blackmail” from Western leaders and he singled out ex-PM Liz Truss, alleging she made “crazy” comments about preparedness to use nuclear arms when Foreign Secretary.
Mr Biden was far from convinced and said: “If he has no intention, why does he keep talking about it? Why is he talking about the ability to use a tactical nuclear weapon? He’s been very dangerous in how he’s approached this.”
Putin and some officials have said in recent weeks that Russia might use nuclear arms to protect its territorial integrity – seen in the West as an implicit threat to use them to defend parts of Ukraine that Moscow says it has annexed.
Senior aides in Mr Biden’s regime expressed concern over Russia’s intentions to deploy the weaponry as it struggles on the battlefield. John Kirby, his national security spokesman, said Russia might consider using a “dirty bomb” and was setting up a pretext to blame Ukraine.
Kremlin chiefs accused Ukraine of planning such a device, where conventional explosives are laced with radioactive material. Yet Mr Kirby said the US had not seen any signs that Russia would deploy one: “They often blame others for that which they are doing themselves or about to do. So that’s why we have to take that seriously.”
UN inspectors will visit Ukraine at Kyiv’s request to check two sites in order to quash Russia’s claim.
As fighting continued and explosions rocked the eastern Ukraine city of Bakhmut, a senior Kremlin official threatened to “strike” Western satellites helping Kyiv – an untested area of international law.
Foreign ministry aide Konstantin Vorontsov warned: “Quasi-civilian infrastructure may be a legitimate target for a retaliatory strike.” He called the West’s satellite support “an extremely dangerous trend”.
No country has attacked another’s satellite and such action during Russia’s invasion of Ukraine might sharply escalate Russia-US tension.
Ukraine’s military relies on Elon Musk’s SpaceX program for broadband internet beamed from its low-orbit Starlink network. US firms such as Maxar capture images of the war from satellites while many Ukrainian communications devices use the Iridium satellite network.
Mr Kirby said that an attack on US infrastructure would be met with an, unspecified, response.