Secretary of State John Kerry has blasted former NSA contractor Edward Snowden as a “confused” man who “betrayed his country,” rebutting the whistleblower’s claim that his exile in Russia is the fault of the U.S. government.

Kerry's comments came ahead of the scheduled airing on Wednesday evening of Snowden’s first sit-down interview with a U.S. network. In excerpts released by NBC, Snowden — who fled the United States after leaking classified documents detailing massive surveillance by the U.S. government — said he “never intended to end up in Russia.”

“I had a flight booked to Cuba onwards to Latin America, and I was stopped because the United States government decided to revoke my passport and trap me in Moscow airport. So when people ask, ‘Why are you in Russia?’ I say, ‘Please ask the State Department,’” Snowden said.

Kerry reacted bluntly to the accusation. “For a supposedly smart guy, that’s a pretty dumb answer,” he told NBC. Snowden has previously said he acted out of “good conscience” to protect privacy and basic liberties.

“If he cares so much about America and he believes in America, he should trust in the American system of justice,” Kerry said. “But to be hiding in Russia, an authoritarian country, and to have just admitted that he was really trying to get to Cuba — I mean, what does that tell you? I think he’s confused, I think it’s very sad, but this is a man who has done great damage to his country.”

Snowden also claimed in the interview that he was trained as a spy and has worked undercover and overseas for both the National Security Agency (NSA) and the CIA, comments that Kerry would not address Wednesday morning.

“I was trained as a spy in sort of the traditional sense of the word, in that I lived and worked undercover overseas pretending to work in a job that I’m not and even being assigned a name that was not mine,” Snowden said. “When they say I’m a low-level systems administrator, that I don’t know what I’m talking about, I’d say it’s somewhat misleading.”

While working as a computer network administrator, Snowden removed tens of thousands of secret documents from an NSA facility in Hawaii and then leaked them to the media. The aftermath of those leaks shook the American intelligence establishment and resulted in Snowden being charged with espionage and other offenses in the U.S. He could face 30 years in prison if convicted.

Kerry, meanwhile, told CBS on Wednesday that Snowden’s actions had harmed national security and that through his actions he had “told terrorists what they can now do to be able to avoid detection.”

“He should man up and come back to the United States if he has a complaint about what’s the matter with American surveillance, come back here and stand in our system of justice and make his case,” Kerry said. “But instead he is just sitting [in Russia] taking potshots at his country.”