“Intelligence reports indicated that the Khorasan Group was in the final stages of plans to execute major attacks against Western targets and potentially the U.S. homeland,” Army Lt. Gen. William Mayville, director of operations of the Joint Chiefs of Staff, told reporters Tuesday at the Pentagon.

Defense analysts said that signals intelligence or Sigint — the result of intercepted communications — likely played a major role because developing spies in war-wracked Syria has been difficult at best and often results in unreliable information.

The NSA has weathered a barrage of criticism since last year, when rogue contractor Edward Snowden leaked to the news media reams of top-secret documents about how the Fort Meade, Maryland-based agency vacuums up mountains of phone and Internet data.