(CNN) -

Hillary Clinton said Friday NSA leaker Edward Snowden should be able to defend himself if he returns to the United States.

"In any case that I'm aware of as a former lawyer, he has a right to mount a defense," she told the UK-based Guardian, which published classified documents last year that detailed U.S. surveillance programs and were obtained by Snowden. Clinton is in Europe promoting her new book, "Hard Choices."

"And he certainly has a right to launch both a legal defense and a public defense, which can of course affect the legal defense," Clinton continued.

Snowden was granted temporary asylum in Russia, where he's been living since last June. If he comes back to the U.S., he could face charges of espionage and theft of government property.

"Whether he chooses to return or not is up to him. He certainly can stay in Russia, apparently under Putin's protection, for the rest of his life if that's what he chooses. But if he is serious about engaging in the debate then he could take the opportunity to come back and have that debate," she said. "But that's his decision."

Snowden told NBC News in May that he considers himself a patriot and felt that he was doing due diligence by unveiling the agency's spy secrets. He said he would eventually like to return to the United States.

"If I could go anywhere in the world, that place would be home," he said in the interview.

Clinton has been critical about Snowden in the past.

"His leaks revealed some of America's most sensitive classified intelligence programs," Clinton wrote in her new book, "Hard Choices."

After a few paragraphs, though, Clinton finds herself somewhere between liberty and security and without answering a number of those questions on domestic surveillance.

"With liberty and security, it's not that the more you have of one, the less you have of the other. In fact I believe they make each other possible," Clinton concludes. "Without security, liberty is fragile. Without liberty, security is oppressive. The challenge is finding the proper measure: enough security to safeguard our freedoms, but not so much (or so little) as to endanger them."