WASHINGTON » Edward J. Snowden says he was not merely a "low-level analyst" writing computer code for U.S. spies, as President Barack Obama and other administration officials have portrayed him. Instead, he says, he was a trained spy who worked under assumed names overseas for the CIA and the National Security Agency.

Snowden’s claims were made in a television interview to be broadcast Wednesday evening by NBC News. They added a new twist to the yearlong public relations battle between the administration and Snowden, who is living under asylum in Moscow to escape prosecution for leaking thousands of classified files detailing extensive U.S. surveillance programs at home and abroad.

"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 told Brian Williams of NBC News, in an excerpt released in advance of the full interview.

The NSA, which has described Snowden as an information technology contractor, has not commented on the new claims.

Snowden also addressed how he wound up in Russia after initially fleeing to Hong Kong.

"The reality is I never intended to end up in Russia," he said in a second excerpt broadcast on NBC’s "Today Show." "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.’"

That comment drew a sharp reaction from Secretary of State John Kerry, in an interview on the same program.

"For a supposedly smart guy, that’s a pretty dumb answer, frankly," Kerry said. He added: "He can come home, but he’s a fugitive from justice, which is why he’s not being permitted to fly around the world. It’s that simple."

Snowden suggested that the government was deliberately playing down his role, although in the excerpt he did not say why.

"What they’re trying to do," he said, "is they’re trying to use one position that I’ve had in a career here or there to distract from the totality of my experience, which is that I’ve worked for the Central Intelligence Agency undercover overseas, I’ve worked for the National Security Agency undercover overseas and I’ve worked for the Defense Intelligence Agency as a lecturer at the Joint Counterintelligence Training Academy, where I developed sources and methods for keeping our information and people secure in the most hostile and dangerous environments around the world."

Snowden said, however, that he had not been the kind of spy depicted by Hollywood who embeds himself in glamorous overseas locations to extract information through interpersonal connections.

"I am a technical specialist," he said. "I am a technical expert. I don’t work with people. I don’t recruit agents. What I do is I put systems to work for the United States. And I’ve done that at all levels from — from the bottom on the ground all the way to the top. Now, the government might deny these things, they might frame it in certain ways and say, ‘Oh well, you know, he’s — he’s a low level analyst.’?"

The interview, which Williams said required the television network to employ its own brand of misdirection and intrigue, was conducted in Moscow last week and will be aired Wednesday starting at 10 p.m. ET.

According to government officials and former colleagues, Snowden first went to work as a security guard at an NSA-financed language research center at the University of Maryland. His computer skills evidently attracted attention, and he subsequently worked overseas for the CIA in Geneva and for NSA contractors in Japan, Maryland and Hawaii before flying to Hong Kong last year and handing secret NSA documents to several journalists.

According to his resume and interviews, he worked in cyber-counterintelligence, searching classified government computer systems looking for intrusions from hackers and foreign spies. In his last job in Hawaii, he was described as an "infrastructure analyst," which former NSA officials say probably meant that he was looking for vulnerabilities in foreign telephone and Internet systems that would allow the agency to tap in.

CIA and NSA employees deployed overseas almost always work undercover, meaning that they are given an official job title, usually as a diplomat, along with business cards and often a false name, to conceal their real role as an intelligence officer. Such employees undergo basic training in how to operate undercover, and Snowden would have had such training before being posted outside the United States.

Kerry, in a CBS News interview Wednesday, suggested that Snowden’s refusal to return to the United States amounted to cowardice.

"The bottom line is this is a man who has betrayed his country, who is sitting in Russia, an authoritarian country, where he has taken refuge," he said. "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. But instead he is just sitting there taking potshots at his country, violating his oath that he took when he took on the job he took."