Annual terror threat report under scrutiny after recent Mideast unrest.
Top U.S. security officials are now calling the killings at the U.S. consulate in Benghazi, Libya last week a terrorist attack.
What remains under debate is whether that attack was planned or spontaneous.
Sitting before the Senate Homeland Security Committee Wednesday three of the top U.S. security officials called the deadly assault on the consulate, where four Americans died, evidence the U.S. continues to be vulnerable to terrorist attacks.
"They died as a result of a terrorist attack," National Counterterrorism Center Director Matt Olsen said bluntly.
But much else remains unanswered or under dispute.
Was Al Qaeda involved?
"We are looking at indications individuals may have had connections to al Qaeda," Olsen testified.