Russia could return Edward Snowden to the US as a “gift” to President Donald Trump, according to two US intelligence sources cited by NBC News on Friday.

One unnamed official, who NBC said gleaned information from “a series of highly sensitive intelligence reports,” said such a move could be an attempt to “curry favor” with the Trump administration.

Snowden is a former US National Security Agency contractor who stole top-secret documents in 2013 that revealed mass surveillance efforts by the US government. He shared those documents with journalists. Russia has been sheltering Snowden since 2013, and recently granted him permission to stay through 2020.

Trump has in the past called Snowden a traitor and a spy, and suggested Snowden may have given US secrets to other countries. Snowden denied those allegations on Friday, saying on Twitter, “I never cooperated with Russian intel. No country trades away spies, as the rest would fear they’re next.”