Some may think that Harry Styles' addition to the cast of World War II epic movie "Dunkirk" is just another publicity stunt, but director Christopher Nolan had absolutely no idea how famous the pop star was, at first.

"I don't think I was that aware really of how famous Harry was," Nolan said in a statement, Friday. He also said that although he heard his kids talk about the former One Direction member, he was not really aware before he casted Styles into the movie, which debuts July 21.

The critically acclaimed director then emphasized that he chose Styles because he fits the role of Tommy "wonderfully." To date, there are no details about the star's part in the movie. Only the name of his character has been mentioned in several news outlets. Many suggest that he is playing a lead role, but that remains to be confirmed.

Last year, photographs of Styles doing "Victory Parade" scenes in Dorset, giving eager fans an idea of who Tommy could possibly be. In one snap, Styles was sticking half his body out of a train window, seemingly bidding someone afar good-bye while drinking a bottle of beer. He was also wearing a military uniform that was covered in blood and mud. This made fans believe that his character is going to be killed off in war.

Although Styles' fellow cast members have been mum about his role, they have defended his talent several times. For instance, Cillian Murphy told the Radio Times that he found the former boyband member to be a "great kid" and "really funny." He pointed out, "Chris knows talent and would have cast Harry for a reason."

Even the movie's casting director, John Papsidera, himself backed up Nolan's decision. In an interview with GQ, he agreed that Styles was "absolutely right" for the part of Tommy. "As an actor he is unknown, but his readings made him an obvious choice," Papsidera explained.

Other members in the cast of "Dunkirk" are Tom Hardy, Kenneth Branagh, Mark Rylance, and James D'Arcy.