WASHINGTON: US President Joe Biden said Monday that it’s “clear” Russia is considering the use of chemical and biological weapons in Ukraine and warned of a “severe” Western response if it chose to do so.

“His back is against the wall,” said Biden of Russian President Vladimir Putin, noting 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.

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His warning echoed statements made by his administration earlier this month as well as other Western nations, after Russian officials accused Ukraine of seeking to hide an alleged US-backed chemical weapons program.

“Now that Russia has made these false claims… we should all be on the lookout for Russia to possibly use chemical or biological weapons in Ukraine, or to create a false flag operation using them,” tweeted White House Press Secretary Jen Psaki.

Biden on Monday also reiterated that such an action would prompt a “severe” but so far undefined response from Western allies.

Putin “knows there’ll be severe consequences because of the united NATO front,” he said, without specifying what actions the alliance would take.

At the same event, Biden noted that he had warned Putin of a US response if Russia launched cyber attacks against US critical infrastructure.

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“We had a long conversation about if he uses it, what will be the consequence,” said Biden, referring to a summit with the Russian leader last year in Geneva.

Earlier in the day, Biden issued a statement warning the US business community of intelligence pointing to a growing Russian cyber threat and urging companies to “immediately” prepare defenses.

“If you have not already done so, I urge our private sector partners to harden your cyber defenses immediately,” he said, citing “evolving intelligence that the Russian government is exploring options for potential cyberattacks” including in response to Western sanctions over Moscow’s invasion of Ukraine.

“It’s part of Russia’s playbook,” he said.

His statement added that the US government would “continue to use every tool to deter, disrupt, and if necessary, respond to cyberattacks against critical infrastructure.”

However, he underlined that most critical infrastructure in the country is owned and operated by private entities, which cannot be compelled to take specific cyber security measures.