Permissive Action Link

PAL is short for Permissive Action Link. The PAL key was an ArmsTech designed security system used as a safety device to regulate the release and launch of nuclear warheads at the nuclear disposal site on Shadow Moses Island.

The original security system, also a PAL, was set up to require two passwords. When these two passwords were entered separately, they would either arm or disarm the nuke, depending on its current state. They were known only by ArmsTech president Kenneth Baker and DARPA chief Donald Anderson.

When these two people died during the Shadow Moses incident, Liquid Snake, the mastermind behind the FOXHOUND rebellion, needed another way to activate the nuke. Leading Solid Snake to believe the nuke was already armed, he arranged for Snake to obtain the PAL keys and use them.

The PAL key was a safety device that had the exact same function as the passwords. There were three different PAL keys, however, there was technically only one physical key; the key was made of a Shape Memory Alloy which allowed the key to change shape into its brothers at different temperatures, functioning as three keys in one.