The 17 veterans, who were responsible for firing nuclear missiles if ever ordered to by previous US presidents, said Donald Trump needed to be stripped of his power.
They said he and any other future president should not be placed in a position where they alone have sole authority to launch a nuclear weapon.
Mr Trump, they said in an open letter, had appeared unsuited to such responsibility during the US election campaign and had only proved this since.
The letter said: “In the final weeks of the presidential election, we sounded our alarm over Donald Trump’s fitness to serve as commander-in-chief, with absolute authority over the nation’s nuclear arsenal.
“One year into the Trump presidency, our alarm has only intensified and we must raise our voices again. The president has had ample opportunity to educate and humble himself to the grave responsibilities of his office.
“Instead, he consistently shows himself to be easily baited, stubborn in his ignorance of world politics and diplomacy, and quick to brandish nuclear threats. The reality of this presidency is worse than we feared.”
They said Mr Trump’s bizarre Twitter outbursts against North Korea and Kim Jong-un had puttee USA on “collision course” for war with the hermit state.
And they said conciliatory comments from South Korea, and the recent thawing in relations between north and south, had given Mr Trump the impression his reckless comments were working.
They said Mr Trump inability to grasp the severity of the situation meant America and the world was more at risk than ever.
The letter said: “Every one of these episodes points to a flaw in the nuclear launch process that poses a clear and present danger to the country and the world: every American president has absolute authority to order the first use of nuclear weapons.
“We and our nation cannot abide being hostages to the mood swings of a petulant and foolish commander-in-chief.
READ MORE: What will Donald Trump do about North Korea’s nuclear war programme?
“No individual, especially Donald Trump, should hold the absolute power to destroy nations.
“That is a clear lesson of this presidency and one that we, as former stewards of the launch keys, embrace with full conviction.”