McMaster says US should take Putin's nuclear threats 'seriously' but says if Russia uses a nuclear weapon 'it's a suicide weapon'

• Former national security adviser Lt. Gen. H.R. McMaster called Putin's nuclear threats "suicide."
• McMaster told CBS that Putin's threats should not shift the West's support for Ukraine.

Former national security adviser, Lt. Gen. H.R. McMaster, said Sunday that Vladimir Putin's threats of using nuclear weapons would be "suicide" if the Russian leader were to deploy them.

The world has been considering how to handle Putin's recent threat to launch nuclear weapons amid the months-long war with Ukraine. A Latvia defense official previously told Insider that Putin is "bluffing" and is a test to see the reaction from Western nations.

During an interview with CBS's "Face the Nation," moderator Margaret Brennan asked McMaster who served as one of President Donald Trump's national security advisers, his thoughts on what the response should be in the wake of Putin's threats.

"I think the message to him is if you use a nuclear weapon, it's a suicide weapon," he said.

"And the response from NATO and the United States doesn't have to be nuclear," he added, referring to the North Atlantic Treaty Organization, a military alliance of various nations.

McMaster, who served as one of former President Donald Trump's national security advisers, said he believes Putin is under "extreme pressure."

"I don't think a nuclear weapon is usable there," he later added. "So, I think that we ought to take it seriously. We have to, but we ought to not allow this to cow us in terms of the support for the Ukrainians."

Along with the nuclear warning, Putin also announced the partial mobilization of his country's reservists, a move that is likely to heighten the ongoing war in Ukraine, according to Insider's Jake Epstein, John Haltiwanger, and Dhany Osman.

"Putin is now upping the ante and he's counting on the fact that we won't go to nuclear war for Ukraine which will get the West to tell Ukraine to negotiate a solution that is basically a Russian victory," Paul D'Anieri, a political science professor at the University of California, Riverside told Insider's Erin Snodgrass.

On "Face the Nation," Brennan asked McMaster about Ukrainian forces entering Lyman, a key eastern city, this past week after Putin declared the region Russian territory.

"This is a tremendous victory for the Ukrainians," he said. "And it's a victory that I think that they could turn into a cascading series of defeats of Russian forces."