Retired Army Lt. Gen. Michael Flynn has been an outspoken supporter of Donald Trump, offering some credibility to the foreign policy newcomer.
But on a key priority of the GOP presidential nominee — banning travel to the United States from areas affected by terrorism — Flynn acknowledged some of Trump's ideas are "not workable."
In a Morning Edition interview, NPR's Steve Inskeep asked Flynn, "In the end do we have here a laudable effort to protect the United States from all harm that is just not workable at all?"
"Well, I think that's a great question to ask, and I would love to hear that question, Steve, asked in one of the upcoming debates," Flynn responded.
He said he believed that "our responsibility is for safety and protection of American citizens abroad and at home," but that will require having "to think differently and we have to use some imagination, and we have to still protect our American values and what we represent to the rest of the world."
Flynn appeared to agree that a travel ban on countries affected by terrorism — which could include European allies such as France or the United Kingdom — may not be the best approach.
"To put a blanket [ban] on any organization, any segment of the population, is not workable, but we do have to recognize what types of things must we be able to do to continue to protect our own country and our way of life, " Flynn said.
The comments by Flynn, the former head of the Defense Intelligence Agency, came on Monday during an interview about his new book, The Field of Fight: How We Can Win the Global War Against Radical Islam and Its Allies.
Like Trump, Flynn believes more forceful measures must be taken to protect the U.S. from the threat of what Flynn calls "radical Islamism."
Trump's proposals have evolved since last December, when he first called for a temporary ban on Muslims entering the United States. Facing a storm of criticism that he was violating principles of religious freedom, in June Trump proposed "suspend[ing] immigration from areas of the world where there is a proven history of terrorism against the United States."
"This is not about a permanent ban," Flynn said. "This is about understanding what is happening with this rapid rise of radical Islamism. And we know, Steve, that the Islamic State has, and they've stated it, they actually stated it in their various media outlets, that they are going to infiltrate into the refugee populations that are entering different countries around the world."