Tom Cruise is said to fear he could be the target of an attack from terrorists or a crazed fan.
He's reported to have tightened up security at the LA home he shares with wife Katie Holmes, 29, after 2 anthrax threats were sent to United Artists, the film studio he runs.
The entire premises were evacuated on both occasions, although fortunately the warnings turned out to be hoaxes.
But Tom, 45, doesn't want to take any risks with his family.
'Tom fears the threats were directed at him,' a source tells the Mail On Sunday.
'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.'
Tom has adopted children Connor, 13, and Isabella, 15, with ex Nicole Kidman, 41, and Suri, 2, with Katie.
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