U.S. President Barack Obama says the United States is using "all the appropriate legal channels" to try to apprehend the fugitive intelligence contractor who disclosed clandestine American surveillance programs.
The White House on Monday said it believes Edward Snowden is in Russia and is pressuring Moscow to expel him to face espionage charges in the United States.
In his secretive hide-and-seek run for asylum, Snowden had been booked on a Monday flight from Moscow to Havana, with his possible eventual destination Ecuador, where he is seeking asylum. But the flight to the Cuban capital left with no sign of him on board.
WikiLeaks founder Julian Assange, whose secret-disclosing organization is assisting Snowden, said Snowden is safe, but he declined to disclose where he is.
White House spokesman Jay Carney said the U.S. has frequently returned criminal suspects to Russia, and said it expects Russia to turn over the 30-year-old Snowden to American authorities.
"Given our intensified cooperation with Russia after the Boston Marathon bombings, and our history of working with Russia on law enforcement matters, including returning numerous high-level criminals back to Russia at the request of the Russian government, that we do expect the Russian government to look at all the options available to them to expel Mr. Snowden back to the United States," he said.
Carney criticized China for what he said was Beijing's "deliberate choice" to allow Snowden to fly Sunday from Hong Kong to Moscow. He said the Chinese decision "unquestionably" damaged relations between the U.S. and China.
U.S. Secretary of State John Kerry, on a visit to India, said U.S. authorities "don't know, specifically, where [Snowden] may head, or what his intended destination may be."
The diplomat told VOA that the programs Snowden divulged have damaged U.S. counterterrorism efforts, and could cost lives.
"This man just took real information and put it out there because he happens to believe something that is not in fact justified by the facts. I think he has put counterterrorism at risk. He has put individuals at risk. And it may well be that lives will be lost in the United States because terrorists now have knowledge of something they need to avoid that they did not have knowledge of before he did this," he said.
Ecuador's foreign minister, Richard Patino, said at a news conference in Vietnam that Snowden has asked for asylum but he "can't give information on Snowden's whereabouts." Patino said his government has been in contact with Moscow.
Kerry said it "would be deeply troubling" for Hong Kong and Russia to allow Snowden to continue his international journey to escape prosecution in the U.S.
National Security Council spokeswoman Caitlin Hayden says the White House is disappointed that Snowden was allowed to leave Hong Kong despite a "legally valid" request for his arrest. The statement early Monday says the United States has registered "strong objections" with authorities in Hong Kong and the Chinese government. Assange said Snowden had a "refugee document of passage" from the Ecuadorian government before leaving Hong Kong.
Ecuador says it is analyzing Snowden's request for asylum. Patino said Ecuador would consider the asylum request based on the "principles of its constitution."
Quito has often criticized U.S. foreign policy, and Patino noted that the U.S. has refused in the past to extradite "fugitive bankers...who have hurt the interests of many Ecuadorians."
U.S. officials say Snowden's passport was revoked before he left Hong Kong for Moscow. The government has advised countries where Snowden may pass through or serve as his final destination that he is wanted on felony charges and should not be allowed to travel internationally.
Ecuador has sheltered Assange at its London embassy for the past year to prevent his possible extradition to Sweden where he is under investigation for sexual assault. His lawyers say Assange fears he will be sent to the United States in connection with the group's publication of secret U.S. diplomatic cables in 2010.
Snowden leaked documents showing that U.S. intelligence services have gathered data for years about patterns of telephone and Internet use. He said he believes the programs violate the privacy rights of citizens.
A senior administration official sharply criticized Snowden's motives, saying his focus on transparency and individual rights "is belied by the protectors he has potentially chosen." The official listed China, Russia, Cuba, Venezuela and Ecuador, saying Snowden's failure to criticize those governments shows his "true motive" was to harm U.S. national security.
Senior U.S. officials have said the surveillance programs do not monitor the content of phone conversations, but look for patterns in the metadata, including information on the time, date and numbers called.
U.S. authorities also have said the programs prevented at least 50 terrorist attacks worldwide since the September 11, 2001 attacks on the United States. They have accused Snowden of weakening their ability to foil future plots.
Some information for this report was provided by AP and Reuters.