The National Security Agency has the ability to record 100 percent of a certain foreign country's phone calls, and rewind the conversations to review them for up to a month after they happen, according to a report from The Washington Post published Tuesday.
It's unclear which country the report refers to, as The Washington Post said it was withholding identifying details at the request of U.S. officials. But the newspaper also said "high-volume eavesdropping may soon be extended to other countries, if it has not been already."
The Washington Post relied on both interviews with anonymous sources close to the surveillance program and documents supplied by former NSA contractor Edward Snowden. The Washington Post and The Guardian were the first to report on the NSA's PRISM surveillance program Snowden leaked last year.
The "voice interception program" is called MYSTIC, according to The Washington Post, and the RETRO voice retrieval system "reached full capacity against the first target nation in 2011."
In that initial deployment, the system is recording “every single” conversation in this unnamed nation and storing the billions of calls "in a 30-day rolling buffer that clears the oldest calls as new ones arrive," the newspaper said.
The NSA would not comment on the specific allegations in Tuesday's report. NSA spokeswoman Vanee Vines emailed NBC News what she said is the same statement the agency sent to The Washington Post.
"It is NSA’s mandate to identify threats within the large and complex system of modern global communications," the statement began. The agency "does not conduct signals intelligence collection" at home or abroad, it continued, unless it is "necessary" to protect national security or citizens of America and its allies.
The NSA punched back at the report in its statement: "Continuous and selective reporting of specific techniques and tools used for legitimate US foreign intelligence activities is highly detrimental to the national security of the United States and of our allies, and places at risk those we are sworn to protect."