The top terrorism threat to the U.S.: al Qaeda affiliates. That's what the FBI Chief is telling a House hearing.

FOX News Radio's Jared Halpern reports from Washington:

Specifically, FBI Director Robert Mueller cites al Qaeda in the Arabian Peninsula. The group responsible for the latest attempt to blow-up a U.S. bound airliner.

(Mueller) "We in the Bureau are currently exploiting an IED, Improvised Explosive Device, seized overseas."

But Mueller is revealing little else about that underwear bomb recovered by a would-be suicide bomber, who was actually working as double agent.

Mueller says that plot demonstrates why Congress must renew wide-ranging surveillance authority set to expire at the end of this year.

In Washington, Jared Halpern, FOX News Radio.