The widely-accepted name for a system developed by the former Soviet Union to allow the country to retaliate against a nation aggressor (though let's be honest, we all know who they meant) should a nuclear strike destroy or incapacitate the Soviet leadership. Such a strike is called nuclear decapitation.
In fact the U.S. also has a similar system, though it is slightly - slightly - less terrifying in its execution. Both share the predictable goal of nuking the aggressor back to the Stone Age, despite the destruction of the home country and much of civilization. Basically the last word in "if I go down, I'm taking you with me."
The Soviet system was developed in the 1970s in line with its doctrine of centralised control over all of the Union's machinations. It became operational sometime during the 1980s. According to one source the West did not even know it existed until a 1993 article on it in the New York Times (one of the sources for this writeup), penned by a former Minuteman launch officer citing unnamed Russian sources. The Soviet leadership used a procedure that would guarantee a nuclear retaliation, in the event of their being killed or incapacitated by a nuclear attack.
How was this ensured? Communications between the Soviet leadership and the General Staff (the country's highest military organisation; the U.S equivalent is the Joint Chiefs of Staff), various installations such as radar tracking stations, missile silos and military command centres were/are all monitored. If a sudden loss of communications occurs, together with the detection of nuclear explosions (how this was/is monitored for is unclear), the system activates and retaliates. Destruction complete, case closed, crisis over.
In 1984 the system was tested, though at the time it was unknown outside the Soviet Union that it was anything beyond a missile test. Two ballistic missile firings were detected by Western surveillance satellites, spaced about 40 minutes apart. An SS-20 communications rocket was launched from Kapustin Yar; after a flight of about 35 minutes it relayed launch instructions to an SS-18 missile silo in Kazakhstan, which fired a test missile that impacted on the Kamchatka Peninsula.
This is a handy illustration of how the system would work. Should the system be triggered, a series of ballistic missiles would be launched from predetermined sites around the country. The missiles, in place of their 'regular' payload of nuclear warheads, carry communication packages. They fly such trajectories as to collectively overfly virtually every nuclear missile silo in the Soviet Union, (presumably) now the Russian Federation. When in range of each respective installation, the missile relays an electronic launch command which locks out external (read: human) commands at the silo, which then automatically launches its missiles. There is some discrepancy between sources as to whether the system is automatically or manually activated; some state the system is automatically triggered once the preconditions are met, others state that a small number of operators are required to trigger the system but that it subsequently operates automatically.
Russia has purportedly continued spending money to keep the system current, including the construction of new communication facilities to relay launch instructions to Russian boomers. Facilities are currently being built under about 1000ft of granite in the Ural Mountains and it is believed by many that they are intended to support the Dead Hand system. One of the installations is reported to include the huge extremely low frequency communications equipment needed to transmit to submarines worldwide.
There is no recorded name for the U.S. system so I'll just refer to it as the Doomsday Machine, another common moniker for the Soviet/Russian version. The Doomsday Machine (DM), like Dead Hand, works off a nationwide network of sensors and monitors on communication lines. These monitors are placed on links between, for example, command centres such as NORAD and nuclear missile silos, or early warning radar stations.
The DM is triggered upon detection of a number of nuclear explosions and the simultaneous loss of communications between these facilities. Upon detection of this, a series of ballistic missiles are launched from around the country. As with the Soviet/Russian system these missiles contain communication packages. Between them they overfly every nuclear missile silo in the continental U.S. (possibly missile regiments based abroad are also covered, though I could not find confirmation of this). On passing each missile silo a message is relayed containing an order to the installation commander to launch all missiles, together with the PAL key codes required for doing so. The commanders, human hesitation notwithstanding, then proceed to launch their missiles.
The difference here is that there is room for human error - should the Russian system be triggered by accident there would be no way to stop it, short of shooting down the communication rockets. Having said that, if any country has the capability to do that at the time of writing it's probably Russia.
One thing that popped up a couple of times during the limited research that was possible for this subject is the idea that if you want to destroy America, 'all' you have to do is nuke Russia. Stay with me. Since the Mutual Detargeting agreement between Russia and America (subsequently adopted by Britain too), the nuclear missiles of each country are no longer aimed at the other. Ignore that said agreement has, at best, symbolic significance. Instead, consider that while most American ICBMs are currently targeted at various oceans (Trident and Peacekeeper missiles have no targets), Russian missiles all have no targets and if launched without change, would automatically revert back to their default targets. Guess where they are?*
If one could ape the conditions of a nuclear attack taking place in Russia (the simultaneous severing of multiple, critical communication lines and the foiling of enough nuclear explosion sensors) the country, like the world's deadliest headless chicken, may launch all of its ICBMs against the United States. I am avoiding certainty here because I do not know whether the system is triggered manually or automatically. I will also take this opportunity to say that the Dead Hand system is not universally accepted as existing. Still, in considering that possibility, consider also the U.S's recent interest in nuclear bunker-buster bombs and that the Jane's Information Group - not exactly a bastion of frenzied, unfounded speculation - has reportedly confirmed the existence of the system.
It is worth noting that with the current Russian policy by which nuclear launch codes are disseminated to lower level officers, nuclear launch authority is essentially delegated to local commanders. This authority could be employed regardless of any Dead Hand system, if it was believed that the Russian leadership had been destroyed by nuclear bombardment.
Sources do disagree somewhat on the current usability of the system. Some paint it as being the most up-to-date system in the Russian military, while others as a decaying relic of a country clinging to the belief in the Western Imperialist Enemy (if there is a difference). Still others declare its present status unknown. Certainly there were fears that the system might be triggered on January 1, 2000 because of year 2000 problem clashing with ageing Russian equipment. Still, an interesting perspective on the belief that a nuclear war can be won, and the lengths to which tit for tat can be taken.
The book 'Dead Hand', by Harold Coyle, is a tale of the system's accidental activation by an asteroid strike. It sounds pretty bad.
Master Villian says re Dead Hand nuclear retaliation - it's like they watched Dr Strangelove and missed the point.
Before you /msg me telling me I'm talking out of my arse, let me say that the limited number of available sources for this subject, together with my status as a slightly-more-informed-than-normal nobody means this writeup should perhaps be considered slightly higher than speculation. Interesting speculation, though.
* - the launch command may contain target data too, rendering this point irrelevant. It would certainly make sense if targets were supplied, though if the system has not, in fact, been updated then it is just as likely that they would be old, Cold War-era targets.
Sources:
- Sanders, Kevin; "Y2K, Nuclear Weapons and Nuclear Power";
<http://www.co-intelligence.org/y2k_nukes1.html>
- Blair, Bruce G;
- "Russia's Doomsday Machine";
<http://www.brook.edu/dybdocroot/Views/Op-Ed/Blair/19931008.htm>
- "We Keep Building Nukes For All the Wrong Reasons";
<http://www.peaceredding.org/washingtonpost_com%20We%20Keep%20Building%20Nukes%20For%20All%20the%20Wrong%20Reasons.htm>
Jasinski, Michael; "Russia: Strategic Early Warning, Command and Control, and Missile Defense Overview";
<http://www.nti.org/db/nisprofs/russia/weapons/abmc3/c3abmovr.htm>
FAS Public Interest Report; "Launch on Warning: Basic Russian Plan";
<http://www.fas.org/faspir/pir0198.htm>
"NATIONAL DEFENSE AUTHORIZATION ACT FOR FISCAL YEAR 1998 (House of Representatives - June 20, 1997)";
<http://www.fas.org/nuke/control/detarget/docs/970620-cr.htm>