Exiled whistleblower Edward Snowden would expose National Security Agency secrets all over again if he got the chance to travel back in time and rethink his actions, according to Joseph Gordon-Levitt.

The actor plays Snowden in Oliver Stone's new movie of the same name and he met the computer expert who exposed the NSA's efforts to control information passed between citizens, in Moscow, Russia as he researched the role.

And he believes Snowden would do exactly what he did in 2013 all over again - even though his actions led to his exile upon threat of arrest if he ever returned to America.

"He doesn't want to live in Russia for the rest of his life, but I think he's encouraged by the changes that have happened since he made the disclosures," Gordon-Levitt tells WENN.

"His first leak revealed that every phone call in America, the metadata, was being recorded by the NSA, and that was ruled unconstitutional by a federal court and was shut down. The USA Freedom Act was passed. So that's progress.

"The former Attorney General sort of admitted that what he (Snowden) did was a service to the country. Even the President has admitted in certain respects the government was overreaching. There really has been a turning of the tide and I think he's encouraged by that and feels that the sacrifice he made wasn't in vain. He's the type of guy that cares more about that than his own personal life."

Snowden himself is a big fan of the film and his parents have patted Joseph on the back for a job well done in portraying their son, but the actor insists his director deserves all the credit for agreeing to make the movie in the first place.

"Oliver is the only filmmaker who could have done this," he tells WENN. "When you think about it, he's the only director in American cinema on a big mainstream scale, large production Hollywood entertaining movies, who is willing to outright criticize the government. That's patriotism.

"I love this country and what it stands for but the government is doing something that goes against our principles and we should all take a look at this. There really isn't another filmmaker who has done that so pointedly and so courageously as Oliver Stone. If you're gonna tell the Edward Snowden story, he's really the only guy to do it."