Tom Cruise has heightened security at the Los Angeles mansion he shares with wife Katie Holmes and their 2-year-old daughter Suri after fears that the 45-year-old acting vet could be the target of a terrorist attack.

Tom has been walking on eggshells since a pair of anthrax threats were sent to United Artists Film Studio he runs.

“Tom fears the threats were directed at him,” a source tells the Daily Mail. “He has tightened security in the office and the Scientology church in Hollywood and installed state-of-the-art cameras at his mansion in Beverly Hills. It’s like Fort Knox.”