June 5, 2013: The British newspaper The Guardian reveals the existence of a secret US court order forcing US telephone company Verizon to provide the National Security Agency with daily information on its customers' calls, from April to July.
June 6, 2013: The Washington Post and The Guardian report that the NSA and the FBI have access to the servers of major Internet companies such as Microsoft, Yahoo!, Google and Facebook so as to monitor the web traffic of people outside the United States.
The program, called PRISM and in effect since 2007, stems from a law approved under the presidency of George W Bush and renewed in December 2012.
The Internet companies deny they have given the government backdoor access to their servers.
June 7, 2013: President Barack Obama says America has to find a balance between privacy and security.
June 9, 2013: As US authorities announce they have started an investigation, Snowden, in hiding in Hong Kong since May 20, reveals himself to be the source of the leak. He does so in an interview with The Guardian.
June 10, 2013: Snowden leaves the Hong Kong hotel where he had been staying. His whereabouts remain unknown to this day. Some US lawmakers call for his extradition.
June 11, 2013: The American Civil Liberties Union files a lawsuit against the telephone record collecting program, calling it unconstitutional.
June 12, 2013: The European Union toughens its tone with the United States and asks for clarifications regarding PRISM.
NSA director Keith Alexander defends the programs and assures they were approved by the court system and Congress.
Snowden resurfaces, in an interview with the South China Morning Post, and says he wants to stay in Hong Kong and that the US monitors hundreds of thousands of computers around the world, including some in Hong Kong and China.
June 13, 2013: FBI director Robert Mueller confirms a criminal investigation is underway against Snowden, and defends the snooping programs as essential to the fight against terrorism.
June 15, 2013: Facebook and Microsoft, aiming for transparency, reveal that in the second half of 2012 they received thousands of requests from US authorities for information about their customers (6,000 to 7,000 in the case of Microsoft, and between 9,000 and 10,000 for Facebook).
June 17, 2013: Apple says it received between 4,000 and 5,000 requests for information from December 2012 to May 2013. The next day Yahoo! says it got 12,000 to 13,000.
June 18, 2013: The NSA director says the surveillance programs helped thwart more than 50 potential terrorist attacks since the September 11 attacks of 2001.
June 21, 2013: Snowden is charged with espionage by US authorities, who ask Hong Kong to arrest him.
A day earlier,a businessman linked to WikiLeaks says people in Iceland are preparing a flight to that country for Snowden to take asylum.
June 22, 2013: The Guardian, quoting documents released by Snowden, says Britain's electronic eavesdropping agency as of last year was handling 600 million "telephone events" a day. Snowden is quoted as saying Britain is worse than the US when it comes to such snooping.
June 23, 2013: Snowden flies to Moscow but does not emerge with other passengers. Russian President Vladimir Putin says Snowden is in the transit zone at Sheremetyevo Airport. The United States revokes Snowden's passport .
June 24, 2013: A Russian plane that is expected to carry Snowden to Cuba leaves Moscow without him on board, sending dozens of journalists on a $2,000, 12-hour wild-goose chase.
June 27, 2013: Obama says he would not "scramble jets" to intercept any flights carrying Snowden.
June 30, 2013: German weekly Der Spiegel says the European Union was another target of Washington's spy programme, sparking demands for explanations from EU, French and German officials.
July 1, 2013: Putin says Snowden is welcome to stay in Russia if he stops leaking intelligence reports and insists "Russia never hands over anybody anywhere". WikiLeaks reveals he has sent asylum requests to 21 nations.
July 2, 2013: Austria, Brazil, Finland, Germany, Iceland, India, the Netherlands, Norway, Poland, Spain - later followed by France and Italy - all refuse to grant Snowden asylum.
July 3, 2013: A diplomatic spat erupts after a flight carrying Bolivian President Evo Morales is forced to stop in Vienna, over suspicions he was travelling with Snowden.
July 5, 2013: Bolivia, Nicaragua and Venezuela say they are willing to take him in.
July 11, 2013: Washington tells China it is "very disappointed" it did not turn over Snowden.
July 12, 2013: Snowden tells a group of activists at the Moscow airport that he wants to claim asylum in Russia until he can go legally to Latin America. Russia should grant Snowden asylum, says Sergei Naryshkin, speaker of Russia's lower house. Obama speaks with Putin after the White House warns Moscow not to give Snowden a "propaganda platform".
July 14, 2013: Journalist Glenn Greenwald says that Snowden has data that could prove far more "damaging" to the US but has chosen not to release them.
July 15, 2013: Putin accuses the US of "trapping" Snowden in Moscow, and says he would leave Russia as soon as possible.
July 16, 2013: Snowden has applied for temporary asylum in Russia, through the Federal Migration Service (FMS), lawyer Anatoly Kucherena tells AFP.