Western knowledge of security and safety features on Soviet nuclear weapons comes from a variety of sources.  A few key details have emerged from exchanges of data that nuclear weapons experts in the two countries have conducted.  As far back as the Kennedy administration, U.S. officials recognized the benefit of ensuring that Soviet military planners and weapon designers were abreast of technological developments that would bolster the security of nuclear weapons.  But until recently, Soviet experts had been disinclined to say much during these exchanges.  Often the American participants simply presented their views without eliciting more than a perfunctory response.  Since early 1990, however, when contacts on the matter increased, Soviet officials have been more willing to discuss the precautions they have taken against an unauthorized or accidental launch.

Other information comes from specialized Soviet publications and statements in the Soviet press.  Although Soviet officials almost never speak openly about particular aspects of nuclear warhead design, their general references to weapon features can shed a good deal of light for well-trained Western observers.  Moreover, on a few occasions Soviet experts have made specific mention of weapon security devices, as in May 1990 when a high-ranking military officer, General Geli Batenin, discussed these features at considerable length.

Finally, some information comes from technical inference and analysis.  For example, Western observers who know the size and yield of Soviet warheads (through overhead reconnaissance, interception of telemetry, and seismological measurement) can estimate, with considerable accuracy, whether the weapons are equipped with one of the most important safety features, insensitive high explosives.  Similarly, changes in Soviet deployment and handling procedures--such as the mating of delivery vehicles and warheads in the mid-1960s--can often reveal the presence (or absence) of security and safety features.

Based on these sources of information, there is every reason to believe that Soviet nuclear weapons, particularly long-range missiles that are on permanent combat alert, are equipped with a variety of "negative" and "positive" features that would prevent unauthorized use.  "Negative" security mechanisms, such as permissive-action links ([cm;1]pal[cm;0]s) and other use-denial features, physically prevent a nuclear weapon from being used until unique authorization codes are received from the national command and the requisite firing procedures are implemented.  Insurgent groups would have no access to the codes needed to initiate a missile launch or a nuclear explosion.

Soviet weapons also have been equipped with anti-diversion membranes and sensors, which are designed to render a weapon inert (by disrupting the fissile material and other components) if any unauthorized disturbance occurs.  Such devices are particularly useful for weapons that cannot be fully safeguarded by standard means (e.g. nuclear land mines).  Furthermore, even if the [cm;1]pal[cm;0]s, anti-diversion mechanisms, and other features were not enough, Soviet leaders could rely on command-disable devices to prevent weapons from being used.  The command-disable features permit stored weapons to be remotely neutralized in an emergency.  All these devices, in combination, would pose an insuperable barrier to the most technologically sophisticated intruder.

Thus, even in the highly unlikely event that a band of insurgents captured a nuclear weapon, the weapon would be physically unusable and could be rendered inert (and therefore unrecyclable).  No separatist groups would be able to resort to nuclear warfare to settle their grievances.

It would behoove the United States to avoid giving the Soviet (or Russian) regime an unwarranted pretext for demanding aid and for retaining control over the non-Slavic regions.  The Soviet government has just as much interest as the United States in ensuring that Soviet nuclear weapons remain secure.  That is precisely why Soviet leaders, to their credit, long ago began taking measures to bolster the security of their weapons.  Even the hardliners who tried to oust Gorbachev had no intention of doing anything that would risk a nuclear conflagration.

This is not to say that American officials should be complacent about the dangers of instability in the Soviet Union or should dismiss the nuclear threat out of hand.  If massive violent unrest were to erupt in the Ukraine before independence, there would certainly be a threat to the nuclear missiles still located in that republic (though even then, it is inconceivable that Ukrainian insurgents would actually be able to fire any weapons they might capture).

More important, as the Russian government increasingly overshadows the central Soviet government, a stable transfer of command authority will have to be arranged.  The remote possibility that some sort of danger will arise during this transfer should worry, though by no means preoccupy, American leaders.  There is little the United States can do to reduce that hypothetical threat, aside from offering advice about weapons security.  Obviously, the U.S. government should continue, and expand, its policy of cooperating with Soviet (and Russian) experts to make weapons more secure.  But what the United States should not be doing is lending credence to outdated claims whose main purpose was to justify the provision of Western aid or to guarantee that the non-Slavic republics would never become independent.

Mark Kramer is a research fellow at the Center for Foreign Policy Development at Brown University and a fellow at Harvard University's Russian Research Center.