Fifty national security advisers and experts who served in Republican administrations from Richard Nixon to George W. Bush have come out with a new letter expressing dismay, concern and outright fear about Donald Trump’s ability to lead the nation and keep the country safe.

The letter, which was first reported by the New York Times, declares their opposition plainly.

“None of us will vote for Donald Trump,” it said although it says later that not voting for Trump did not necessarily mean everyone would be supporting Clinton.

The letter goes on to say that Trump “lacks the character, values and experience to be president,” that he “weakens U.S. moral authority,” “appears to lack the basic knowledge about and belief in the U.S. Constitution, U.S. laws and U.S. institutions including religious tolerance, freedom of the press, and an independent judiciary.”

Trump, the letter accuses has “alarmed” American allies with his “erratic behavior.”

In the last month, Trump has indicated he was moving away from the U.S. NATO alliance, he has continued to soften his posture toward Russia and continued to blast trade deals Republicans have traditionally supported. His attacks against a Gold Star family has only added to concerns that Trump lacks the poise to serve as the country’s Commander In Chief.

In their open letter, national security operatives noted that “Mr. Trump has demonstrated repeatedly that he has little understanding of America’s vital national interests, its complex diplomatic challenges, its indispensable alliances, and the Democratic values that on which U.S. foreign policy must be based.”

The letter included more names than the March open letter decrying Trump, a symptom of Trump’s continued bluster and peculiar backtracking on foreign policy principles that most leaders in this country have taken for granted for decades.

The letter went on to blast Trump’s “temperament.” The letter noted that a president must be able to both surround himself and listen to key advisers. There was doubt Trump could do that.

“Donald Trump is not the answer,” the letter read.

The letter was signed by high-profile figures including former Secretary of Homeland Security Michael Chertoff, Former CIA director Michael Hayden and John Negroponte, the former Director of National Intelligence.