Russia’s invasion of Ukraine is leading some U.S. politicians, experts and world leaders to question President Vladimir Putin’s mental stability.

Former U.S. Secretary of State Condoleezza Rice, who served under President George W. Bush, called Putin’s recent behavior "erratic."

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"I met with him many times, and this is a different Putin," she said on Fox News Sunday. "He was always calculating and cold, but this is different. He seems erratic. There is an ever deepening, delusional rendering of history."

Russia President Vladimir Putin in Moscow

Russian President Vladimir Putin gives a thumbs-up as he attends a foundation-laying ceremony for the third reactor of the Akkuyu nuclear plant in Turkey March 10, 2021.  (Sputnik/Alexei Druzhinin/Kremlin via REUTERS/File Photo)

Former Director of National Intelligence Jim Clapper echoed Rice’s assessment of the Russian ruler, who has grown increasingly frustrated over his failure to swiftly subdue Ukrainian forces.

"I personally think he’s unhinged," Clapper said Sunday on CNN. "I worry about his acuity and balance."

The concerns about Putin’s shaky mental health are particularly relevant given that he has his finger on the nuclear trigger, Clapper added.

Senior intelligence officials who have known Putin for decades told Fox News that he has been isolated for months at his presidential compound interacting exclusively with a small group of advisers and cronies.

Czech President Milos Zeman 2021

President of the Czech Republic Milos Zeman addresses the media June 10, 2021. (AP Photo/Lisa Leutner, File)

A senior national security official under President Donald Trump, who asked for anonymity, said when Putin met with French President Emmanuel Macron earlier this month, he seemed "paranoid" and "unwilling to listen to reason."

During the meeting in Moscow, the men sat across an absurdly long marble table, as Macron tried to persuade Putin to stand down. After the failed effort at intervention, Macron privately described Putin as "more rigid, more isolated and fundamentally lost in a sort of ideological and security drift," according to a senior French official.

Longtime Putin ally, Czech President Milos Zeman, called the Russia leader a "madman" this week after he launched the invasion, according to The Guardian.

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But Rebekah Koffler, former DIA intelligence officer and author of "Putin’s Playbook: Russia’s Secret Plan to Defeat America," told Fox News Digital that Putin is no mad man.

"Putin is absolutely not crazy. All this talk calling him crazy, it means we’re still not taking Putin seriously or understanding him," said Koffler,

"He’s not delusional, there are no mental anomalies," she added. "Putin is a cold-blooded, typical Russian autocratic leader and a very calculated risk-taker. He’s simply executing a plan that he has been hatching for 20 years."

Koffler said that calling Putin crazy is a cover-up for the U.S failure to appreciate Putin's ambitions or psychology. 

President Joe Biden initially called the use of sanctions a deterrent. After the invasion, he reversed course and said he actually didn't think the economic penalties would prevent war.

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"If anything, this conflict has exposed our lack of a viable counter-strategy to Putin's well-thought-out plan," Koffler said.  "We’re grasping at straws right now."

Gillian Turner and the Associated Press contributed to this report