The effort is the latest known expansion of the N.S.A.’s warrantless surveillance program, which allows the government to intercept Americans’ cross-border communications if the target is a foreigner abroad. While the N.S.A. has long searched for specific email addresses and phone numbers of foreign intelligence targets, the Obama administration three years ago started allowing the agency to search its communications streams for less-identifying Internet protocol addresses or strings of harmful computer code.
To carry out the orders, the F.B.I. negotiated in 2012 to use the N.S.A.’s system for monitoring Internet traffic crossing “chokepoints operated by U.S. providers through which international communications enter and leave the United States,” according to a 2012 N.S.A. document. The N.S.A. would send the intercepted traffic to the bureau’s “cyberdata repository” in Quantico, Virginia.