U.S. President Donald Trump gestures during a cabinet meeting at the White House in Washington, D.C., U.S., August 26, 2025. REUTERS/Jonathan Ernst

President Donald Trump may be too mentally compromised to hold the nation's highest office, according to one national security expert.

In a Tuesday post to her X account, journalist Juliette Kayyem — who is a CNN analyst and professor at Harvard University's Kennedy School of Government — quote-posted a video of Trump's comments in the Oval Office about sending National Guard troops to Chicago, Illinois. In the video, Trump was asked about the legality of such a move, prompting him to respond that he had ultimate legal authority given his position.

"I would have much more respect for [Illinois Governor JB] Pritzker if he called me up and said 'I have a problem, can you help me fix it,' I would be so happy to do it," Trump said. "I have the right to do anything I want to do, I'm the president of the United States. If I think our country is in danger — and it is in danger in these cities — I can do it."

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In her response to the video, Kayyem wrote that Trump was "incorrect" in his belief that he could do "anything" as president.

"He either believes it is true and is therefore unfit to be president or believes it is a lie and same," she tweeted. "The third option is that he is not of sound mind and body and all I can do is watch how he speaks and moves and it is a fair question to ask now."

As Pritzker mentioned in a speech this week, Trump following through on his threat to send U.S. military forces to Illinois' largest city would be "unprecedented." The Posse Comitatus Act of 1878 prevents the military from being used as domestic law enforcement personnel. And the president's Title 32 authority he's using to send National Guard troops to multiple states still gives governors and adjutant generals full control over those forces (which could be why he's only sending guardsmen to states with Republican governors).

Trump, who is currently 79 years old, is the oldest president to ever be inaugurated. At the time of his second swearing-in, Trump was 78 years and 220 days old, beating out former President Joe Biden's previous record of 78 years and 61 days old.

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