The FBI increased its use of secret search warrants last year due to what a top official calls a "high tempo of terrorist activity.”
FBI Assistant Director John Miller said that 2,176 Foreign Intelligence Surveillance Act search warrants were approved last year, compared with 1,754 granted in 2005. Most of the warrants involved plotters inside America.
"We're seeing a very high tempo of terrorist activity, not just based on the cases you're seeing being brought in the United States," Miller said in an interview Wednesday with C-SPAN.
Miller believes the U.S. may have underestimated top al-Qaida leaders' ability to oversee operations in recent years, the New York Daily News reports.
Story Continues Below
Al-Qaida is "getting more effective" at planning new strikes while using propaganda to inspire others to "take that ball and run with it," Miller said.