A guest post by John Donovan, the Armorer of Castle Arrgghhh (and Lizzie)
Nuke weapons design and policy are governed by the need for safety and control. PALs are a component of control.
What is a PAL? PAL stands for Permissive Action Link. The purpose of the PAL is not to prevent unauthorized use of a nuclear weapon by rogue elements of the US military command. We do that via the EMAS (Emergency Message Authentication System) and NRAS (Nuclear Release Authentication System) systems and the imposition of strict two-person control (at a minimum) at each step of the process.
Some of those processes can be longer than others, depending on whether the weapons involved are “first strike deterrent” weapons like the USAF ballistic missiles and the USN SLBMs (Submarine Launched Ballistic Missiles) or further down the chain like the manned bombers, cruise missiles and formerly, US Army tactical nuclear missiles and artillery. PALS are also distinct from
safeties. Safeties are intended to prevent premature or accidental initiation or partial initiation of a warhead.
PALS have a different niche.
NATO airbase, mid-sixties. NATO fighter-bomber, fully fueled and armed, sits on “strip alert,” pilot strapped in. A lone US Airman armed with an M1 carbine stands guard. He is literally the only thing standing between chaos and disaster should that non-US NATO pilot decide (or get told by his government) to light up his jet and go bomb a target. Soviet or not. (1)
US Army Warhead Detachment, Mid-70s. NATO ally army trucks and some tanks roll up to the Detachment’s gate. The purpose of the detachment is to secure and maintain nuclear warheads (missile or artillery) stored in NATO nations that are there for either US units, or, upon authorization, NATO
units. Tensions are erupting between the ally and another nation and signals intelligence indicates that the ally’s generals have been talking to each other about taking some of the warheads to use as a lever against the other belligerent. While the confrontation at the gate never happened, the conversations did. (2)
Hey, NATO Ally – are you my buddy, my pal right now? No? That is why have PALs. To prevent unauthorized people from using US-provided nukes without express authorization from the President of the United States. The problem with both of those scenarios is that besides being scary as hell, it was (and still is) contrary to US law about control of US nukes, i.e., only we could give release, no one could take one of our weapons and use them unilaterally. Only we get to do that.
Yet, we gave nuclear-capable weapon systems to allies – the Nike-Hercules air defense missiles, various US Army tactical missiles like Honest John, Lance, and Pershing, and 155mm and 203mm nuclear artillery projectiles. And many NATO aircraft were nuke-delivery capable. And all that had to be scattered around Central Europe so that those nations could quickly employ them if things got ugly on the North German Plain and the rolling hills of Bavaria along the Czechoslovakian border. Same was true of bombs, and NATO aircraft on Quick Reaction Alert (QRA).
We needed something better than the Airman 1st Class-Mounted M1 Carbine Nuke Weapon Disabler. There are four types of PALs (at least that are acknowledged publicly these days) that are variations on a theme. They are either electrical/digital and integral to the weapon, buried inside where it is hard to get to them, and they interfere with the arming/initiation process until unlocked from an external code transmitted to them, or they are like combination locks that must be unlocked with a code thoughtfully provided by a two-man US warhead team acting under orders with the codes received via the NRAS system. Mechanically removing them will take time, and, most likely, render the warhead inoperative.
Giving hopefully cooler heads time to intervene. A balance between the profound need to control release and the tactical realities of modern combat
“Bypassinag a PAL should be, as one weapons designer graphically put it, about as complex as performing a tonsillectomy while entering the patient from the wrong end.” (3)
Acknowledgements and further reading, if you want further unclassified details.
A useful unclassified and easy-to-read discussion of PALs.
Steven M. Bellovin Permissive Action Links (columbia.edu) A useful unclassified and easy-to-read discussion of PALs.
A drier, more technical discussion of both Safety and Control. Subscription to the Bulletin is required to access the archived articles.
U.S. Nuclear Weapons Safety and Control Features To cite this article: (1991) U.S. Nuclear Weapons Safety and Control Features, Bulletin of the Atomic Scientists, 47:8, 48-49, DOI: 10.1080/00963402.1991.11460025 https://doi.org/10.1080/00963402.1991.11460025
Notes
(1) Stein, Peter and Feaver, Peter. Assuring Control of Nuclear Weapons. University Press, 1987
(2) Reed, Thomas C. At the Abyss: An Insider’s History of the Cold War. Presidio Press/Ballantine Books,
2004.
(3) Caldwell, Dan and Zimmerman, Peter D., “Reducing the Risk of Nuclear War with Permissive Action
Links”, in Technology and the Limitation of International Conflict, Blechman, Barry M., ed., Johns
Hopkins Foreign Policy Institute, 1989.
Acknowledgement: The author wishes to acknowledge the sharp eye and excellent editorial instincts of Lizzie, a feline of great discernment. Not only did she keep him company and offer encouragement, she added stray characters and deleted random paragraphs to test this scribbler’s skill. Sic Semper Felinus.
Acknowledgement II: This old wolf wishes to thank John for coming out of blogging retirement, as it were, to add to the Nuclear 201 series and to Lizzie for her contributions as well.
*****
SOME PREVIOUS POSTS:
Nuclear 201 Posts In Order
Nuclear 201: Some History
Nuclear 101 Posts In Order:
Nuclear What?
Nuclear 101: Weapons
Nuclear 101: Delivery
Nuclear 101: Now What?
Nuclear 101: Targeting
Nuclear 101: Scenarios
Nuclear 101: Survival
Some Quick Thoughts
*****
If you would like to help me in my recovery efforts, feel free to hit the tip jar in the upper right or the fundraiser at A New Life on GiveSendGo. Getting hit by lightning is not fun, and it is thanks to your gifts and prayers that I am still going. Thank you.