(NewsNation) — A former U.S. general has growing concerns that Russia might engage in chemical warfare.

“My biggest concern is that the war will escalate, and escalate through weapons of mass destruction — could be through chemical weapons or tactical nuclear weapons,” former Lt. Gen. Richard Newton said Sunday on “NewsNation Prime.”

“In Putin’s playbook, but also in the Soviet-era playbook, is that they will escalate in order to de-escalate,” Newton said. “And so, one of the tools that he could (use to) escalate and really put NATO on its heels, potentially, is the use of chemical weapons.”

Newton is not the only one concerned that Putin might use chemical weapons White House national security adviser Jake Sullivan, noting that Russia is claiming that the U.S. has set up biological weapons laboratories in Ukraine, told NBC’s “Meet the Press” that when Russia starts accusing other countries of preparing to launch biological or chemical attacks, “it’s a good tell that they may be on the cusp of doing it themselves.”

Newton said a chemical attack could be destructive not only in terms of massive human casualties, but that it could leave an area uninhabitable for years. He says that Putin might use them on an open target or out in a field first, to demonstrate that he has the capability and intent to deliver those chemical weapons on a larger scale.

“If he uses them once, he would then have the propensity to use them perhaps multiple times,” Newton said. “That’s where it would be absolutely terrifying. And I think … all bets are off at that point.”

Pentagon spokesman John Kirby, who appeared on ABC’s “This Week,” said, “We haven’t seen anything that indicates some sort of imminent chemical or biological attack right now, but we’re watching this very, very closely.”