The former Central Intelligence Agency director John Brennan has added his name to growing calls for the president to be ousted on grounds that he is unfit for the job, arguing that the US constitution’s 25th amendment addressing involuntary removal from office was “written with Donald Trump in mind”.

Brennan, who served as head of the spy agency during Barack Obama’s presidency, told MS Now on Saturday that Trump’s recent volatile remarks about destroying Iranian civilization and the danger he posed to so many lives merited his removal from the Oval Office.

“This person is clearly unhinged,” he said. “I think the 25th amendment was written with Donald Trump in mind.”

Brennan added that Trump was too much of a liability to be allowed to continue to be commander in chief. He had immense firepower at his disposal, including the US nuclear arsenal.