WASHINGTON – A new unit at the FBI is focusing on preventing an attack on the United States with chemical, biological or nuclear weapons, FBI Director Robert Mueller said Wednesday.

The FBI has hired Vahid Majidi, a chemist from the Los Alamos National Laboratory in New Mexico, to run the new weapons of mass destruction directorate, Mueller said at a briefing for reporters at FBI headquarters.

“I think it is fair to say that anyone who is concerned about the safety of this country and the future, their concern is weapons of mass destruction and particularly weapons of mass destruction in the hands of terrorists,” Mueller said.

The WMD office is part of the latest reorganization at the FBI since the Sept. 11, 2001 terrorist attacks.

Al Qaida’s leadership has been damaged by U.S. anti-terror efforts over the past five years, but the group retains the capacity to launch a future attack on the United States, Mueller said.

And a growing number of people in the United States who have no affiliation with al Qaida nevertheless share its view that “the killing of innocents to meet an end is acceptable,” said Philip Mudd, the No. 2 official in the FBI’s new national security branch.

U.S. authorities last month arrested seven men in a plot to attack Chicago’s Sears Tower and government buildings. Prosecutors say the plot was in the preliminary stages and that the suspects had no ties to al Qaida.

Majidi said his office looks at the range of possible attacks from the individual who mails an envelope filled with white powder to efforts to detonate a nuclear weapon on U.S. soil.