By Melissa Fares

(Reuters) - Actor Bradley Cooper is developing a TV miniseries based on a book about the rise of Islamic State militants, a show the author hopes will help Americans understand how the group came about.

Joby Warrick's 2016 Pulitzer Prize-winning book, “Black Flags: The Rise of ISIS" tracks the group’s unlikely roots and transformation into the jihadist ensemble, from its origins in a remote Jordanian prison to its advances in Syria.

The non-fiction book also follows the small band of American and international agents tasked with shutting down the group.

"Delighted to finally be able to make this news public," Warrick, 56, said via a Twitter post on Thursday.

Cooper, best known for his starring roles in movies like "American Sniper" and "The Hangover," is developing the miniseries for HBO through his production company, the cable channel said. It will dramatize events in the book.

Warrick, a national security reporter at the Washington Post, said the series would aim to explain, educate and help clarify issues about the Islamic State group and its motivations, a subject he had discussed with Cooper which was of immediate and utmost importance to American citizens.

"It’s entertainment but it’s not purely entertainment," Warrick told Reuters on Friday. "The story is in good hands."

Warrick said Cooper, 41, and partner producer Todd Phillips, 45, had visited him at his home outside of Washington, D.C. earlier this year to pitch their idea.

"When you write a book of nonfiction on an important subject, you're flattered that there is film interest but you’re also a little worried," Warrick said.

"You wonder: How will it be transformed?" Warrick said, noting that while he would not be writing the script, the film team has made him "feel like a partner" in asking for his input.

"I came away feeling very impressed with the integrity of their ideas."

No casting or estimated air date has been announced for the "Black Flags" project.

Cooper and Phillips formed their production company, Joint Effort, in 2014. Their project “War Dogs,” a comedy about arms dealers in Afghanistan in which Cooper also stars, will be released Aug. 19.

(Reporting by Melissa Fares in New York; Editing by Jill Serjeant and Bernadette Baum)