Among the signatories are former officials from the Reagan administration; others who served both George Bush and George W. Bush; and a few, like John Negroponte, the former director of national intelligence, and General Michael Hayden, who served as director of the Central Intelligence Agency and the National Security Agency and whose service extended over both Democratic and Republican administrations.
The letter also includes a handful of midlevel officials who served under Mr. Trump. But the list of signatories misses most of the biggest names in national security who entered the administration, only to be fired or resign. Among those missing are Rex Tillerson, the former secretary of state, and three former generals who served in high posts: John Kelly, the former chief of staff; H.R. McMaster, the former national security adviser; and Jim Mattis, the former defense secretary.
John R. Bolton, who was fired as national security adviser last year, has said publicly that he would not vote for Mr. Trump, but has refused to embrace Mr. Biden, saying he would write in a conservative Republican instead.
When the first letter was released in 2016, it had some shock value: No one could recall when established national security leaders had abandoned the party’s nominee. Today, the critiques sound more familiar, though the new letter picks through more than three years of international chaos to argue that Mr. Trump has “gravely damaged America’s role as a world leader” by mocking allies, and soliciting foreign influence in American elections.
As the most recent letter laid out, Mr. Trump “proclaimed his ‘love’ and ‘great respect’ for the North Korean strongman Kim Jong-un, endorsed ‘brilliant leader’ Xi Jinping’s move to serve as China’s president for life,” and “repeatedly sided with Vladimir Putin against our own intelligence community.”
Yet within the Republican national security establishment, there are arguments about whether such letters actually harm Mr. Trump or help him.
Peter Feaver, a veteran of the Clinton and Bush administrations, who helped draft several versions of the 2016 letter, decided not to sign the one released on Thursday.