From New Mind.

▶️ Visit https://brilliant.org/NewMind to get a 30-day free trial + 20% off your annual subscription

In the early days of nuclear weapons, security measures were surprisingly basic. This video explores the fascinating history and development of Permissive Action Links (PALs), the sophisticated systems that now safeguard nuclear arsenals.

Timeline:
1940s-1950s: Primitive security measures
– Weapons kept partially disassembled
– No formal policy on custody, control, and proliferation
– Simple 3-digit combination locks introduced

1953: Missiles and Rockets agreements
– Defined roles of Atomic Energy Commission (AEC) and Department of Defense (DoD)

1961: Committees formed to study use control
– Special Warhead Arming Control (SWAC) Committee
– Safety Steering Group
– Joint Command and Control Study Group Project 106

August 1961: Secretary of Defense requests AEC to create permissive links for NATO weapons

June 1962: President Kennedy issues NSAM 160
– Mandates PALs on all U.S. nuclear weapons in NATO countries

How PALs Work:
1. Isolation: Critical components enclosed in "exclusion region"
2. Incompatibility: Designed to prevent accidental activation
3. Inoperability: "Weak links" render weapon inoperable in extreme conditions

Key Components:
– Stronglinks: Rugged electromechanical devices controlling weapon arming
– Energy control elements: Create pathways into exclusion region

PAL Categories:

Category A (1960s):
– MC1541 coded switch (5-digit code)
– Complex operation, took 30 seconds to 2.5 minutes
– Required multiple support equipment pieces

Category B (mid-1960s):
– MC1707 coded switch (4-digit code)
– Faster operation, cockpit control possible
– Fewer wires, parallel unlocking for multiple weapons

Category C (mid-1970s):
– Extended Cat B capabilities
– 6-digit code
– Introduced limited code attempt lockouts

Category D (1975):
– First microprocessor-based PAL (MC2764)
– Multiple Code Coded-Switch (MCCS) concept
– 6-digit codes for various functions (arm, train, disable)
– Interfaced with MC2969 Intent stronglink
– Anti-intrusion sensors, some self-powered

Category F (mid-1980s):
– 12-digit code system
– Advanced features: code-driven disable modes, emergency stops
– Variable yield adjustment via code
– Encryption in the arming process

Key Developments:
1980s: Modernization efforts
– Second-generation stronglinks: detonator and dual magnetic
– Improved reliability and reduced manufacturing costs

1997: PALs installed on all U.S. nuclear devices
– U.S. Navy last to receive them

2001: PAL Code Management System (CMS) deployed
– End-to-end encrypted method for re-coding weapons
– MC4519 MCCS Encryption Translator Assembly

2004: CMS fully implemented across all PAL systems

Future Developments:
– Ongoing miniaturization and ruggedization
– Micromachining technologies for mm-sized components

SUPPORT NEW MIND ON PATREON
https://www.patreon.com/newmind

#NuclearSecurity #PermissiveActionLinks #MilitaryHistory #DefenseTechnology #NuclearWeapons #ColdWar