THREATCON

In United States security, Force Protection Condition (FPCON for short) is a terrorist threat system overseen by the United States Department of Defense directive, and describes the amount of measures needed to be taken by security agencies in response to various levels of terrorist threats against military facilities, as opposed to DEFCON, which assesses the amount of military forces needed to be deployed in a situation with a certain likelihood of attack against the civilian population. The decision on what level of FPCON to implement is affected by the current threat of terrorism towards military facilities and personnel, the amount of security forces available, and current relationships between the United States and the world, which may affect the chances of an attack. FPCON was previously known as THREATCON, until it was renamed in June 2001 due to confusion with United States State Department system of threat assessment.

There are five Force Protection Conditions; the commander of U.S. Northern Command determines what the minimum force protection level will be for every American installation in the continental United States. USNORTHCOM sets the force protection condition level for so many installations because it is the Unified Combatant Command whose geographic area of responsibility is North America. Other combatant commands, such as U.S. European Command and U.S. Southern Command, set the force protection condition levels for American military installations in their areas of responsibility. Individual facility and installation commanders may increase their local force protection levels as they feel is necessary, but they must adhere to at least the minimum level prescribed by USNORTHCOM. Force protection can include procedures as basic as checking identification cards at the entrance to an installation and requiring credentials to get inside a building. However, when necessary, force protection procedures can become as stringent as inspecting every vehicle, person and bag entering an installation. The five Force Protection Conditions are:

...
Wikipedia