Although his lawyer said previously that he would need to decide whether to stay in Russia or return to the United States, Snowden is now only a year away from legally being able to claim citizenship. "In effect, he now has all grounds to receive citizenship in the future, over the course of a certain period, since under the law we have a period of residence on Russia soil of not less than five years" said Anatoly Kucherena, Snowden's legal representative.

Yesterday, the White House revealed that the former NSA-contractor turned whistleblower cannot be given a similar reprieve to Chelsea Manning. Snowden won't be granted clemency because he has not filed paperwork seeking such an action, nor has he been formally charged with any crimes. As President Obama said back in November: "I can't pardon somebody who hasn't gone before a court and presented themselves."

The exact reasons why Russia decided to extend Snowden's residency aren't known but his lawyer believes that his desire to stay out of the limelight has aided officials' judgement. That doesn't mean he hasn't been critical of his adopted country and stopped him from suggesting that it may have been partly involved in last year's NSA hack.

"Now he has already been living on Russian territory for nearly four years, he does not violate the law, there are no complaints about him," Kucherena said. "That's one of the reasons his residency permit was extended."