Retired Army Lt. Gen. Michael Flynn, a vocal supporter of Donald Trump, spoke in Dallas on Wednesday night about fighting terrorism, the role of Islam in politics and the coming election.

Once on the short list for the Republican nominee's vice president, Flynn served as the director of the Defense Intelligence Agency from 2012 to 2014 and offered some foreign policy credibility to Trump's status as a political newcomer.

He spoke at an event hosted by ACT for America and held at the Studio Movie Grill in northwest Dallas. About 50 people attended the lecture and book signing, the second event held by the Dallas ACT for America chapter.

Flynn's hourlong speech addressed a number of topics but mostly focused on the role of radical Islamic terrorism. He answered a select few audience questions before beginning the book signing.

Is Donald Trump a Republican?

Flynn, a Democrat himself, said he was unsure.

"Donald Trump, is he really a Republican?" he asked.

He acknowledged that Trump has made "all kinds of mistakes out there" and chalked it up to Trump not being a seasoned politician.

"He deeply believes, like I do, in the future of this country," Flynn said.

Flynn described Trump as more of a populist in contrast to Democrats' progressivism.

"When people say progressive, that means socialist," he said. "Bernie Sanders was an avowed Communist and he almost won. What does that say about the left?"

During the campaign, Sanders regularly billed himself as a democratic socialist, a political ideology distinct from communism.