EMC Corp.'s security-systems unit RSA offered to swap theSecurID tokens it provides to clients such as defense contractorsand government agencies after a network breach disclosed in Marchresulted in the theft of RSA data.

RSA will replace the tokens if the customer believes it isnecessary, Helen Stefan, a spokeswoman, said in an interview. Shesaid RSA has about 40 million tokens in use, providing clients'employees remote access to internal networks. Itsdefense-contractor clients include Lockheed Martin Corp., NorthropGrumman Corp. and Raytheon Co.

In March, Hopkinton, Massachusetts-based EMC said that a cyberattack resulted in information being taken from its systems,including data related to RSA's SecurID products. Bethesda,Maryland-based Lockheed Martin, the defense contractor that was thetarget of an attack on May 21, said last week the breach was theresult of the data theft at RSA and that it would replace itssecurity tokens.