The information apparently comes from classified NSA documents leaked by Edward Snowden to Greenwald (and others).

We know a bit about the NSA's connection to America's global capture/kill machine already.

In the 2010 report "Top secret America," Dana Priest and Will Arkin of The Washington Post reported that the NSA provided the capture/kill squads of Joint Special Operations Command (JSOC) with a huge advantage after the signals intelligence agency "learned to locate all electronic signals in Iraq."