It is believed the virus was introduced into the spy agency's network accidentally by someone inserting a floppy disk containing the virus into an agency computer. The virus contaminated less than 1 percent of the network, says the agency, which falls under the authority of the Department of Defense.
Officials say the virus in that system has been contained.
Officials say they do not believe sensitive intelligence information was affected in either that or the NSA system. Spreading the Love Around Two classified e-mail systems at the National Reconnaissance Office, which builds and operates the nation's spy satellites, also were infected, officials say. Those systems were infected by an e-mail orginating from another agency, but the viruses had no impact on reconnaissance operations, an NRO official said. The systems have been temporarily closed down to incoming and outgoing e-mail traffic and the viruses were eliminated, the official said. The military's Joint Task Force on Computer Network Defense has been investigating how the virus entered classified systems.