US President Joe Biden has warned that intelligence points to fears that Russia is considering the use of chemical and biological weapons in Ukraine.
And he warned that if Russian President Vladimir Putin does take that option then there will be a “severe” Western response.
Mr Biden said “His back is against the wall.”
He noted that Russia has recently accused the United States of holding chemical and biological weapons in Europe.
“Simply not true. I guarantee you,” he told a gathering of US business leaders in Washington.
“They are also suggesting that Ukraine has biological and chemical weapons in Ukraine. That’s a clear sign he’s considering using both of those,” he said.
At the same event, Mr Biden noted that he had warned Mr Putin of a US response if Russia launched cyber attacks against US critical infrastructure.
“We had a long conversation about if he uses it, what will be the consequence,” said Mr Biden, referring to a summit with the Russian leader last year in Geneva.
Earlier in the day, Mr Biden issued a statement warning the US business community of intelligence pointing to a growing Russian cyber threat and urging companies to “immediately” prepare defences.
“If you have not already done so, I urge our private sector partners to harden your cyber defenses immediately,” he said.
He cited “evolving intelligence that the Russian government is exploring options for potential cyber attacks” including in response to Western sanctions over the invasion of Ukraine.
“It’s part of Russia’s playbook,” he said.