Edward Snowden, the U.S. National Security Agency’s external-contractor-turned-whistleblower, is said to have hidden away a “massive trove of top-secret data” in encrypted files that would be released publicly should “anything” happen to him, and such revelations could damage U.S. intelligence interests, reports have said.

Mr. Snowden, who is wanted by the U.S. government for making earth-shaking revelations on the NSA’s mass automated surveillance of Internet and telephonic communications, is presently said to be stuck in the international transit area of Moscow’s Sheremetyevo airport, even as he awaits travel documentation from Ecuador after making an asylum application to that country.

However according to unnamed sources speaking to the UK’s Sunday Times, when he left Hong Kong for Russia on June 23, “he did not carry his four laptops to the airport” and encrypted copies of the data on those machines were said to be “locked in a safe or a bank vault.” The Times added that the release of this data could have “devastating consequences for Western security interests, say sources familiar with his time in the Chinese city.”

The suggestion that Mr. Snowden has such an “insurance policy” against attempts to capture or assassinate him is consistent with remarks made by Guardian reporter Glenn Greenwald, who was at the centre of the NSA-surveillance revelations, to the Daily Beast.

Mr. Greenwald has been quoted saying that Mr. Snowden “has taken extreme precautions to make sure many different people around the world have these archives to insure the stories will inevitably be published,” and he added that if anything happened at all to Mr. Snowden, “He told me he has arranged for them to get access to the full archive.”

Mr. Snowden himself warned authorities that he could not be silenced, saying on June 17, “The U.S. government is not going to be able to cover this up by jailing or murdering me... The truth is coming, and it cannot be stopped.”

Reports of Mr. Snowden’s backup plans came even as some intelligence experts called on the U.S. government to limit the damage from the revelations about snooping programmes PRISM and Boundless Informant.

Former Central Intelligence Agency and NSA Director, Michael Hayden, said on CBS News’ “Face the Nation” show this weekend that the government should release more information about how and why phone and Internet records from around the world were being observed by the NSA, so as to reassure Americans that their privacy rights were being protected.

Meanwhile Secretary of State John Kerry defended Washington’s global-scale surveillance, which is authorised by the secretive Foreign Intelligence Surveillance Court, saying on the sidelines of the ASEAN conference on Monday, “Every country in the world that is engaged in international affairs with national security undertakes lots of activities to protect its national security and all kinds of information contributes to that.”

The U.S. faced sharp criticism over the weekend this week after German news weekly Der Spiegel reported on Sunday that the NSA “bugged diplomats from friendly nations – such as the EU offices in Washington, New York and Brussels.” The Indian embassy here was also said to be included in a list of 38 surveillance “targets.

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