WASHINGTON (AP) — U.S. counterterrorism agencies have not detected a significant al-Qaida operational capability in the United States since the 2003 arrest of a truck driver who was in the early stages of plotting to destroy the Brooklyn Bridge.

Never-theless, al-Qaida’s capabilities aren’t clear and the group remains dangerous, the new deputy director of the National Counterterrorism Center, Kevin Brock, said in an Associated Press interview.

The uncertainty reflects the tension facing national security officials even though the country has gone four years without a domestic attack from al-Qaida.

Brock was the FBI’s special agent in charge of the Cincinnati office that investigated Iyman Faris, now serving a 20-year prison sentence for aiding and abetting terrorism and conspiracy. Faris, a Pakistani who became a U.S. citizen in 1999, was exploring whether he could ruin the Brooklyn Bridge by cutting the suspension cables.

Brock said the case showed him al-Qaida’s weakened state following the attacks of Sept. 11, 2001.

“Since the Iyman Faris case and other investigations, the FBI and other agencies are just not detecting an operational capability by the al-Qaida organization in the United States of imminent significance,” Brock said.

Yet he and other senior officials it is not the time to relax.

“We have to assume that they remain a very viable and very dangerous threat,” Brock said. “You almost can’t define al-Qaida just as an entity that you can put on an organizational chart. It has now expanded to an ideology that has gotten quite dangerous.”