The Agency That Could Be Big Brother

By JAMES BAMFORD

Washington

DEEP in a remote, fog-layered hollow near Sugar Grove, W.Va., hidden by fortress-like mountains, sits the country's largest eavesdropping bug. Located in a "radio quiet" zone, the station's large parabolic dishes secretly and silently sweep in millions of private telephone calls and e-mail messages an hour.

Run by the ultrasecret National Security Agency, the listening post intercepts all international communications entering the eastern United States. Another N.S.A. listening post, in Yakima,Wash., eavesdrops on the western half of the country.

A hundred miles or so north of Sugar Grove, in Washington, the N.S.A. has suddenly taken center stage in a political firestorm. The controversy over whether the president broke the law when he secretly ordered the N.S.A. to bypass a special court and conduct warrantless eavesdropping on American citizens has even provoked some Democrats to call for his impeachment.