State Department spokesman Patrick Ventrell rejected comments by WikiLeaks founder Julian Assange, who has described Snowden as being legally "marooned" in Moscow after Washington cancelled the leaker's US passport.
"That's not true," said Ventrell, referring to Assange's remarks.
He told reporters the US government could issue Snowden a "one entry travel document" to the United States as he is "accused of serious felony crimes."
"He's still a US citizen. He still enjoys the rights of his US citizenship, which include the right to a free and fair trial for the crimes he's been accused of."
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Snowden had stopped in Moscow from Hong Kong on June 23 on his way to Latin America, possibly Ecuador, in an attempt to avoid extradition to the United Sates on espionage charges.
The State Department spokesman declined to predict how the United States would respond if Snowden was given asylum in Russia.
"Again, we're not at that point right now. We're going to continue to make our case about what we think needs to happen, and we hope they do the right thing," Ventrell told reporters.
He declined to explicitly acknowledge the alleged electronic eavesdropping, refusing to either defend or apologize over the purported spying. Instead, he insisted the matter would be discussed with allies privately and not publicly.
Ventrell said "the US government will respond appropriately to our partners through diplomatic and intelligence channels."
But he echoed comments from President Barack Obama that seemed to suggest other governments engage in similar spying.
"While we're not going to comment publicly on the specifics of alleged intelligence activities, as a matter of policy, we've made clear that the US gathers foreign intelligence of the type gathered by all nations," he said.