The future of superpower stability and arms control rests on the increasingly vulnerable links between world leaders and the awesome arsenals they control. And it is these less glamorous but extremely important command-and-control facilities - rather than more controversial missiles, submarines, and aircraft - that could determine whether the nuclear balance becomes more stable.
This ability to communicate with forces in the field, as well as the hot-line facilities between Washington and Moscow, is thus likely to be the most important and perhaps stickiest part of coming talks in Geneva, according to many experts.
''In today's world where minutes count . . . we must be capable of quickly determining that the threats and conflicts either do or do not affect the vital interests of the United States and our allies, and then respond appropriately,'' US Defense Secretary Caspar W. Weinberger said this week in a speech titled ''The Uses of Military Power.'' (See story on page 4.)
Mr. Weinberger was speaking of the broad range of possible conflict. But he emphasized that ''in this nuclear age, we measure time in minutes.''
Because the Soviets hold an advantage in heavy intercontinental ballistic missiles with increasingly accurate warheads, US leaders are most concerned about a ''decapitating'' first strike that would leave this country unable to retaliate and hence deter such a strike in the first place. So, too, does the new generation of missile-bearing submarines that lurk just minutes off the US coast.
On the US side, the deployment of extremely accurate Pershing II missiles in Europe, which the Soviet Union says could reach Moscow with almost no warning (American officials deny the new Pershing has this range), the testing of advanced antisatellite weapons, and the push for space-based military systems raises the same concerns in the Kremlin.
''This vulnerability creates a strong incentive for a first strike,'' warns Bruce Blair, project director for strategic command and control at the congressional Office of Technology Assessment and a former US Air Force missile launch officer.
Such vulnerability may be driving both sides toward ''launch on warning,'' and many experts express deep concerns that a superpower nuclear exchange could be triggered not by design but as the result of a Sarajevo-like crisis, which precipitated World War I, that runs out of control.
''It is the crisis behavior of these systems rather than malevolent attack that is my concern,'' said Paul Bracken, an associate professor at Yale University and author of the book ''The Command and Control of Nuclear Forces.''
''The Soviet Union places a great deal of emphasis on counter-command and control strikes'' in their strategic doctrine, Dr. Bracken said at a seminar sponsored by the private Arms Control Association this week. ''They place a high emphasis on going after electrical power grids and AT&T systems because they carry a great deal of our military traffic.''
What to do about it?
The Reagan administration is quietly making improvements in the command-and-control system its top strategic priority. These include a new network of early-warning satellites and massive ground-based radars, hardening of national command facilities (including the continuously airborne communications aircraft) against blast and electromagnetic effects, and more survivable communications links between the president, military commanders, and strategic forces.
Among the new systems are MILSTAR satellites using extremely high-frequency communications, the ground-wave emergency network (GWEN), and additional PAVE PAWS phased-array radars in Texas and Georgia (the other two are in California and Massachusetts) to warn against submarine missile attack, and extremely low-frequency (ELF) antennas in Wisconsin and Michigan to improve communications with US submarines.
While lauding the administration for doing ''a lot of good things in this area,'' Dr. Bracken also cautions that ''if both sides move into outer space, it'll add another layer to the whole problem.''
''The Reagan administration has done more for command and control, but they've also put more demands on it with their nuclear strategy,'' said William Kincade, executive director of the Arms Control Association. ''As we get more adept at controlling weapons, our control of conflict may be getting less and less.''
The US has taken the initiative in improving hot-line facilities to defuse a nuclear crisis. A bilateral accord signed in July will upgrade the hot line (actually a teleprinter) so that it can send messages at three times its current 64 words a minute. It also will be able to transmit graphics as well.
But the Soviet Union has been less willing to agree to such things as a jointly staffed crisis control center or communications links between the Pentagon and Soviet military headquarters, as Mr. Weinberger recommended.
An Aspen Institute study group this week recommended that the West push for a network of such crisis control centers in the capitals of countries with nuclear arsenals. Richard Smoke of Brown University and William Ury of the Harvard Law School say a US-Soviet crisis center could develop standard crisis procedures similar to the Incidents at Sea Agreement, which has helped prevent confrontations at sea from escalating.
''The obvious course of action for arms control . . . is to structure a Soviet-American agreement around banning short-time-of-flight weapons or restricting deployment of systems that can reach national command centers,'' writes Dr. Bracken. ''It might mean, for example, trading deployment of the Pershing II missile for a curtailment of Soviet SSBN (missile submarine) operations near America's coastlines.''