Fifty of America’s top former national security officials have denounced Donald Trump as unfit to be president and commander-in-chief.

In an open letter, they said he would be “a dangerous president and would put at risk our country’s national security and well-being.”

All the officials served in Republican administrations, and all said they would not vote for him, even though he’s their party’s candidate.

Among them is Jendayi Frazer, a former assistant secretary of state for Africa. She was also a special assistant to President George W. Bush on African affairs.

“The letter basically calls into question his character,” says Frazer. “Specifically, looking at his inability to really deal with disagreement. The fact that he spends most of his time putting down those who do not agree with him. That he’s very thin-skinned. It also calls into question his values and whether he has the experience to be the president of the United States.”

“The different people who signed the letter have different positions on policy,” Frazer explains, “but what we have in common is the question about his disposition and his character as that befitting of a person who has out nuclear arsenal at their fingertip.”

None of the signatories will vote for Trump, and some have indicated they’re ready to vote for Democratic nominee Hillary Clinton.

Donald Trump has responded to the letter. The signatories, he said, are "the ones the American people should look to for answers on why the world is a mess, and we thank them for coming forward so everyone in the country knows who deserves the blame for making the world such a dangerous place."

He called them all "nothing more than the failed Washington elite, looking to hold onto their power."  

“I’m not trying to hold on to any power,” responds Frazer. “I’m concerned about how power is exercised in the Oval Office.”

Frazer added that Trump’s comments reaffirm her decision to sign the letter. “Donald Trump typically does what he’s doing right there, which is to personalize, denigrate, and push back without clear deliberation. He doesn’t seem capable of actually listening to what people are saying.”

Frazer says those traits make her concerned for the nation, given the inevitable international crises any president has to try to manage.

“I feel even more convinced and committed to trying to say to the Republican party and to the nation as a whole, this guy doesn’t have the temperament to lead our country."

But not everyone in foreign policy circles thinks all of Trump's ideas about the US' role in the world are fundamentally flawed.

In a new article in Foreign Policy, Harvard University's Stephen Walt says a few reasonable tenets are woven into the billionaire candidate's worldview.

"Trump has occasionally, in his three sensible moments, suggested an alternative way of thinking about American interests and how American power is used that, if he stuck to those, we might be having a fairly interesting discussion," the international relations professor says.

The overlap of Walt's and Trump's worldviews includes the notion that some wealthy countries are not bearing their rightful share of collective security versions. The two also agree that the chief purpose of US foreign policy is to advance US interests, and that "nation-building" efforts abroad are frequently a disaster.

But Walt is quick to point out that, in his opinion, "those three elements pretty much exhaust Trump's wisdom on foreign affairs."

The debate on the global role of the United States and the proper use of American power is "long overdue," Walt laments, especially when it comes to nation-building, and whether Washington should be taking on responsibility for providing security in Europe, in much of the Middle East and in Asia all simultaneously.

"What worries me is because [Trump's] sensible views are also associated with his tendency to engage in racist rhetoric," Walt says, "his weird ideas about international trade, his cavalier remarks about nuclear weapons, that sensible alternative that he occasionally gets close to is going to be unfairly discredited by its association with a candidate that really is in many ways beyond the pale."

From PRI's The World ©2016 PRI