Editing Permissive action link (section)

=== Two-man rule ===
{{main|Two-man rule}}

[[File:SAS Container.png|thumbnail|right|These two locks are part of the implementation of the two-man-rule in a Minuteman ICBM launch control capsule]]

Modern PALs use the [[two-man rule]], which is designed to prevent accidental or malicious [[rocket launch|launch]] of [[nuclear weapon]]s by a single individual.{{fact|date=May 2023}}

For example, on a [[ballistic missile submarine]] (SSBN), both the [[commanding officer]] (CO) and [[executive officer]] (XO) must agree that the order to launch is valid, and then mutually authorize the launch with their operations personnel. Instead of another party confirming a missile launch as in the case of land-based [[ICBM]]s, the set of [[key (lock)|keys]] is distributed among the key personnel on the submarine and kept in safes (each of these crew members has access only to his keys), some of which are locked by [[combination lock]]s. Nobody onboard has the combination to open these safes; the unlock key comes as a part of the launch order from the higher authority.<ref>{{cite news |url=http://www.time.com/time/magazine/article/0,9171,101361-1,00.html |archiveurl=https://web.archive.org/web/20091008111941/http://www.time.com/time/magazine/article/0,9171,101361-1,00.html |archivedate=2009-10-08 |first=Douglas C. |last=Waller |title=Practicing For Doomsday}}</ref>

In the case of [[Minuteman missile]] launch crews, both operators must agree that the launch order is valid by comparing the order's authorization code against a code from a "sealed authenticator" (a special sealed envelope that holds a code). The sealed authenticators are stored in a safe that has two separate [[Lock (security device)|locks]] so that a single crew member cannot open the safe alone. Both crew members must simultaneously turn the four launch keys. An additional safeguard is provided by requiring the crew in another [[Missile launch control center|launch control center]] to do the same for the missiles to be launched.