John Brennan, the former CIA director under President Obama, will talk about security against extremism since 9/11 at a remembrance event in Denver on Sept. 7.

Tickets are on sale for $25 each.

The event, called Colorado Remembers 9/11: Commemoration & Critical Forum on Extremism Crisis, is at 7 p.m. in the Gates Concert Hall at the University of Denver’s Newman Center.

Brennan will be joined by Bret Stephens, who won a Pulitzer Prize for commentary for his Global View column in the Wall Street Journal in 2013. He became an op-ed columnist for The New York Times in April to focus on foreign policy and domestic politics.

In 2015 Brennan drew fire from conservatives for defending President Obama’s decision not to use the word “Islamic” to describe ISIS, the acronym that means “Islamic State of Iraq and Greater Syria,” and other extremists.

“I do think it does injustice to the tenets of religion when we attach a religious moniker to them,” Brennan said during a question-and-answer session at the Center for Foreign Relations in New York City, saying the better word was “psychopathic.”

According to Time magazine’s report on the event:

Brennan said using “Islamic” or “Muslim” to describe ISIS militants gives them “the type of Islamic legitimacy that they are so desperately seeking, but which they don’t deserve at all.”

The Sept. 7 event is co-hosted by Gov. John Hickenlooper and Denver Mayor Michael Hancock. It is sponsored by The Denver Post, The CELL (an acronym for the Counterterrorism Education Learning Lab in Denver) and the University of Denver.