(CNN) -- The global cat-and-mouse hunt for Edward Snowden took a dramatic turn Sunday when the man wanted on U.S. espionage charges fled Hong Kong and reportedly arrived in Russia.
WikiLeaks said in a Twitter post Sunday that Snowden had touched down in Moscow. But the organization, which facilitates the publication of classified information, did not disclose what country would be his final destination.
Snowden, who leaked top-secret details about U.S. surveillance programs, left Hong Kong on Sunday "through a lawful and normal channel," the Hong Kong government said.
He took off with the help of WikiLeaks, which assisted with Snowden's "political asylum in a democratic country, travel papers (and) safe exit from Hong Kong," the group said on Twitter.
Baltasar Garzon, a former Spanish judge and the organization's legal director, said in a statement Sunday that the treatment of Snowden has been "an assault against the people."
"The WikiLeaks legal team and I are interested in preserving Mr. Snowden's rights and protecting him as a person," he said.
Snowden took off not long after the United States asked Hong Kong to extradite the former National Security Agency contractor.
In a statement Sunday, Justice Department spokeswoman Nanda Chitre said Hong Kong authorities had informed U.S. officials of Snowden's departure.
"We will continue to discuss this matter with Hong Kong and pursue relevant law enforcement cooperation with other countries where Mr. Snowden may be attempting to travel," she said.
Hong Kong: Extradition request didn't comply with requirements
The U.S. government had also asked Hong Kong to issue a provisional arrest warrant for Snowden, the Hong Kong Special Administrative Region said in a statement.
But HKSAR officials said there were problems with the request.
"Since the documents provided by the U.S. government did not fully comply with the legal requirements under Hong Kong law, the HKSAR government has requested the U.S. government to provide additional information," Hong Kong officials said.
Because Hong Kong didn't have enough information, "there is no legal basis to restrict Mr. Snowden from leaving Hong Kong," the government said.
A Justice Department official said Sunday that the United States had met requirements with its request, disputing the assertion from authorities in Hong Kong.
"They came back to us with a few questions late Friday and we were in the process of answering those questions," the official said. "We believe we were meeting those requirements. As far as the relationship with Hong Kong goes, this raises questions and we will continue to discuss with authorities there."
Hong Kong's lack of intervention came after Snowden told the Souh China Morning Post that U.S. intelligence agents have been hacking computer networks in Hong Kong and mainland China for years.
Hong Kong said it wanted to have some words with the United States about that.
"The HKSAR government has formally written to the U.S. government requesting clarification on earlier reports about the hacking of computer systems in Hong Kong by U.S. government agencies," Hong Kong officials said in the same statement. "The HKSAR government will continue to follow up on the matter so as to protect the legal rights of the people of Hong Kong."
U.S. federal prosecutors have charged Snowden with theft of government property, unauthorized communication of national defense information, and willful communication of classified communications intelligence to an unauthorized person.
The latter two allegations amount to espionage under the federal Espionage Act.
News of Snowden's departure followed a day of intense speculation over whether Hong Kong would extradite him to the United States.
Hong Kong Executive Council member Regina Ip said authorities could arrest Snowden if his actions qualify as criminal under Hong Kong law, China's state-run Xinhua news agency reported earlier Sunday. The executive council decides on policy matters for Hong Kong, a special administrative region of China.
But if the charges against him were deemed to be political in nature, the 30-year-old would not be extradited, Ip told Xinhua.
How the case unfolded
Snowden has admitted in interviews he was the source behind the leaking of classified documents about the NSA's surveillance programs. Those leaks were the basis of reports in Britain's Guardian newspaper and The Washington Post this month. The Guardian revealed Snowden's identify at his request.
The documents revealed the existence of programs that collect records of domestic telephone calls in the United States and monitor the Internet activity of overseas residents.
The revelation of the leaks rocked the Obama administration and U.S. intelligence community, raising questions about secret operations of the NSA and whether the agency was infringing on American civil liberties.
President Barack Obama, top legislators and national security officials defend the surveillance programs as necessary to combat terrorism and argue that some privacy must be sacrificed in a balanced approach.
They say the law allows collection of metadata, such as the time and numbers of phone calls, and that a special federal court must approve accessing the content -- listening to the call itself.
In interviews this month, Snowden said he fled with the classified documents after taking a leave of absence from his job as an intelligence analyst for NSA contractor Booz Allen Hamilton. The company has since fired him.
A series of blog posts this week purportedly by Snowden said he leaked classified details about U.S. surveillance programs because Obama worsened "abusive" practices, instead of curtailing them as he promised as a candidate.
Snowden said that he had to get out of the United States before the leaks were published by the Guardian and The Washington Post to avoid being targeted by the government.
CNN's Joe Johns, Dan Lothian, AnneClaire Stapleton, Carol Cratty, Melissa Gray and Steve Brusk contributed to this report.
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