The politically-active director admits he is disappointed matters surrounding climate change and international conflict have not been discussed by the wannabes who hope to replace Barack Obama in the White House.

And he is particularly concerned the issue of surveillance is not a big talking point at debates and campaign events as he prepares to released his film about Edward Snowden, the computer expert who was forced into exile after he leaked classified documents detailing the amount of information National Security Agency officials have gathered on U.S. citizens.

"What's disappointing is neither candidate has talked about surveillance," Stone tells WENN. "Nor have they talked about the wars that America is involved in or climate change. It's just an election in which we're in denial of what's going on in the world.

"Our movie is beyond that and I hope it's timeless. Frankly, I think the Snowden issue will be remembered in history far more than this trivial election."

Stone believes Snowden, who is portrayed by Joseph Gordon-Levitt in his film, will also go down in history as a true hero, because he helped to change surveillance laws and shine a light on America's dark secret.

"I remember when it happened and it was quite revelatory," he adds. "I applauded him as a citizen because I think it was the transparency that Obama promised. It was Snowden who delivered it, certainly not Obama."