WASHINGTON, Nov 15: The Al Qaeda network may be plotting “spectacular” attacks inside the United States, with national landmarks or the aviation, oil and nuclear industries as possible targets, the FBI warned even as the nation’s threat level remained unchanged.

With the threat level still at yellow or “elevated,” meaning a significant risk of terror attacks, the FBI said in a bulletin dated on Thursday that the Muslim extremist network may seek to inflict massive casualties, psychological trauma and severe damage to the US economy.

Due to a lack of specific information about any planned attack, the FBI said the nation’s overall threat level would not be raised.

The bulletin cited the release on Tuesday of an audiotaped message supposedly by bin Laden. The voice on the tape praised recent attacks against Western interests around the world and threatened further attacks against the United States and its allies.

In the latest of a series of warnings, the FBI said the audiotape foreshadowed potential attacks.

“In selecting its next targets, sources suggest al Qaeda may favor spectacular attacks that meet several criteria: high symbolic value, mass casualties, severe damage to the US economy and maximum psychological trauma,” the FBI said.

“The highest priority targets remain within the aviation, petroleum, and nuclear sectors as well as significant national landmarks,” it said.

“Sources also suggest that small-scale terrorist operations against softer targets would be easier for sleeper cells already in the US to carry out and would minimize the need to communicate with central leadership, lowering the risks of detection,” the FBI said.

TRUCK BOMBS: “Thus, Al Qaeda’s next attack may rely on conventional explosives and low-technology platforms such as truck bombs, commercial or private aircraft, small watercraft or explosives easily concealed and planted by terrorist operatives,” it said.