Director Oliver Stone has criticised President George Bush, saying he had "set the country back 10 years."
Oliver Stone is promoting his World Trade Center film
Speaking at the San Sebastian International Film Festival, Stone condemned what he saw as the politicisation of the 9/11 attacks.
He claimed the "overreaction" to the attacks had wasted resources, encouraged fanatics and made him "ashamed to be an American".
Stone's new film is about two men who survived inside the World Trade Center.
He told a press conference ahead of the film's screening in Spain: "From September 12 on, the incident was politicised and it has polarised the entire world.
'Waste of energy'
"It is a shame because it is a waste of energy to see that the entire world five years later is still convulsed in the grip of 9/11."
He added: "It's a waste of energy away from things that do matter which is poverty, death, disease, the planet itself and fixing things in our own homes rather than fighting wars with others.
"Mr Bush has set America back 10 years, maybe more."
World Trade Center has received largely favourable reviews in the US, with many being surprised at the normally controversial director's family-friendly treatment on the subject.