The 30-year-old former contractor to the National Security Agency checked in twice for his flight, but did not board the plane, airport officials said.
Snowden "is in a safe place," said WikiLeaks founder Julian Assange, whose organization has been aiding Snowden in his quest for asylum in the weeks since Snowden came forward to take credit for the leak of information about the NSA gathering extensive cell phone records.
Assange would not disclose where Snowden was hiding, but said Ecuador had furnished "refugee" travel documents that would allow Snowden to travel despite the State Department revoking his U.S. passport.
U.S. officials were furious Snowden had been allowed to leave Hong Kong, and relations between the U.S. and China would certainly be affected.
"This was a deliberate choice by the government to release the fugitive despite a valid arrest warrant," said White House Press Secretary Jay Carney Monday. "That decision unquestionably has a negative impact on the U.S.-China relationship."
Carney expressed confidence that the Russian authorities would cooperate with U.S. demands for Snowden to be repatriated as the U.S. has done so for Russian criminals in the past.
"We are expecting the Russians to examine the options available to them to expel Mr. Snowden for his return to the United States," Carney said.
Snowden has been charged with felony espionage.