MYSTIC is a former secret program used since 2009 by the US National Security Agency (NSA) to collect the metadata as well as the content of phone calls from several countries. The program was first revealed in March 2014, based upon documents leaked by Edward Snowden.
MYSTIC operates under the legal authority of Executive Order 12333.
The MYSTIC program started in 2009, but reached its full capability to record the content of phone calls in an entire country for 30 days, in 2011. Documents from 2013 say the surveillance program could be extended to other countries.
On March 18, 2014, the existence of the program was first revealed by The Washington Post, based upon documents leaked by Edward Snowden. It was reported that the NSA had the capability to record all the phone calls from an unidentified foreign country.
On May 19, 2014, the website The Intercept published the name of one country of which the phone calls were recorded, and also identified three other countries of which only the telephony metadata were collected (see below).
Under a sub-program of MYSTIC codenamed SOMALGET, the NSA is actively recording and archiving the content of "virtually every" phone call for thirty days. After thirty days, the recorded calls are overwritten by newer phone calls, although concern was raised that the NSA may start storing collected phone calls indefinitely.
Although NSA analysts can only listen to less than 1% of the phone calls collected under MYSTIC, millions of voice clips are forwarded for processing and storage every month.
A representative of the American Civil Liberties Union (ACLU) criticized the program, stating that the NSA now has the ability to record anything it wants to. It was also noted that MYSTIC is the first revealed NSA surveillance operation capable of monitoring and recording an entire nation's telecommunication system.