Chris Kyle was the most lethal sniper in U.S. military history.

Now, the much-anticipated film about Kyle's life, "American Sniper," is set to hit the big screen on Christmas Day.

Scott McEwen, who co-wrote Kyle's autobiography and was a consultant on the film, joined Steve Doocy on "Fox and Friends" this morning.

McEwen explained that he met Kyle through some Navy SEAL friends. He eventually started recording Kyle's history, because Kyle's story was so compelling and patriotic.

"I felt it was a historical disservice not to have his story recorded, because Chris was really the epitome of a warrior and a patriot of this country," McEwen said.

He said that the film, which was directed by Clint Eastwood, does an excellent job at capturing Kyle, and Bradley Cooper truly transformed into the SEAL, both physically and mentally.

McEwen said that "American Sniper" does more than depict Kyle's deployment to Iraq, it delves into the difficult times that Kyle and his family had to go through while he was serving his country.

"This movie and what Clint Eastwood did with this movie, it's not just a war movie, per se, it's a movie about the toll of war."

"American Sniper" opens at theaters nationwide Christmas Day. Watch the heart-pounding trailer below.