The National Security Agency (NSA) has the ability to record every single one of a foreign country's telephone calls and then play the conversations back up to a month after recording, according to a report by The Washington Post.
The NSA program, which begun in 2009, is known as MYSTIC.
MYSTIC, according to the Post, is used to intercept conversations in just one (undisclosed) country, but planning documents show that the NSA intends to use the system in other countries in the future.
The program, which didn't become fully operational until 2011, is capable of intercepting and recording billions of telephone calls for a period of 30 days. Once that buffer is filled, new calls overwrite the oldest ones.
While previous revelations from Snowden have shown how the NSA has collected metadata associated with phone calls, MYSTIC goes one step further by allowing the collection of entire conversations.
A senior manager within the program told the Post that MYSTIC is comparable to a time machine in that it allows any call to be replayed, even if the participants in the conversation hadn't been flagged for surveillance in advance.
The Washington Post says, at the request of US officials, it will not reveal the country in question, or any other nation where the system has been planned to be put to use. It is, however, quite likely that calls made to or from that nation will include American citizens.
Civil rights groups have already expressed concerns over the program and how it may evolve to encompass many more countries, other purposes and, potentially, hold data for far longer periods of time.
In a press release from the American Civil Liberties Union Jameel Jaffer, the organisation's deputy legal director, said:
This is a truly chilling revelation, and it’s one that underscores how high the stakes are in the debate we’re now having about bulk surveillance. The NSA has always wanted to record everything, and now it has the capacity to do so. The question now is simply whether we have the political will to impose reasonable limits on the NSA’s authority – that is, whether we have the political will to protect our democratic freedoms.
Speaking for the National Security Council, Caitlin Hayden said information sought by the US intelligence community is, in many cases, hidden in the “large and complex system” of global communications.
The United States must consequently collect signals intelligence in bulk in certain circumstances in order to identify these threats.
Hayden said that the presidential directive that authorises this type of collection "makes clear that signals intelligence collected in bulk may only be used to meet specific security requirements."
The NSA itself has not confirmed the existence of the MYSTIC program but an emailed statement from spokeswoman Vanee Vines is perhaps rather telling:
NSA does not conduct signals intelligence collection in any country, or anywhere in the world, unless it is necessary to advance US national security and foreign policy interests and to protect its citizens and the citizens of its allies and partners from harm.
Vines added that publication of classified intelligence programs jeopardises national security.Follow @NakedSecurity