"The US will retaliate forcefully if Russia uses nuclear weapons in Ukraine, President Joe Biden's national security adviser, Jake Sullivan, told CBS on Sunday. He also declared that the referendums in the Donbass republics and Kherson and Zaporozhye Regions of Ukraine had not altered Washington’s support for Kiev.

'Any use of nuclear weapons will be met with catastrophic consequences for Russia,' Sullivan said on the network’s Face the Nation program, explaining that the Biden administration had told Moscow both privately at 'very high levels' and publicly that 'the United States and our allies will respond decisively if Russia uses nuclear weapons...'" [less than 50%] [link to www.rt.com (secure)]