The spy agency has been placing files on visitors' computers
that can track Web surfing activity. Strict federal rules ban most
such files, known as "cookies."

The files vanished from the N-S-A system after a privacy
activist complained and The Associated Press made inquiries this
week. Agency officials admit they made a mistake.

A top official at the Center for Democracy and Technology says
compared to all the N-S-A's other spying ability, "cookies are not
exactly a major concern." But the privacy advocate says by
breaking "the government's very basic rules for Web privacy," the
agency shows it doesn't understand the issue.

An N-S-A spokesman says the cookies were inadvertently allowed
due to a recent software upgrade.