My understanding was that when Grumman pulled out, the contractors implemented a last ditch software change to the Flight Control Computers that effectively grounded every F-14. Apparently this was a well planned contingency for allowing the purchase of such a frontline fighter to Iran. Makes you wonder what other DoD/State Department mandated controls are put into our modern defense sales to other countries. No wonder JSF partners are vying for integral roles in development and maintaining the aircraft. Like GPS, these other countries don't likely appreciate the capability of the US being able to pull the plug on national defense assets. With millions of lines of code, it would be rather easy to hide.