New Yorker writer Ford says that he set out to find out about ""the button"": the thing (whatever it is) that enables an American president to retaliate for a Soviet attack. What he learned should scare the nuclear cobwebs out of anyone who's not already terrified. Simply told, Ford discovered that the capability for a retaliatory strike is tenuous indeed, that the Pentagon knows it, and that any expectation of a nuclear war is centered on an American first strike. The ability to retaliate is based on communications and control of the nuclear arsenal--i.e., on sophisticated satellites, antiquated radar, and telephone, microwave, and other communications technology. The weak link, Ford shows, is that satellite-gathered information must be received on earth in one place and transmitted from there to Colorado to be interpreted and collated with other information. Receiving stations are vulnerable to an early attack (transmitting facilities, such as microwave towers, are vulnerable to sabotage), and no one knows the effect of exploding nuclear weapons either. Radar tracking stations in Greenland, England, and Alaska are all prime targets for the first Soviet missiles; left to their own, they often enough produce false alarms and unclear information. None of this apparatus matters, of course, if the guys in Colorado can't get the Pentagon and the White House on the phone: during a visit to the North American Aerospace Defense Command in the Rockies, Ford looked on while a general eagerly picked up the phone connected to the president only to put it down 20 seconds later when no one answered. (No one answered at the Joint Chiefs of Staff, either.) Communications technology aside, there's the problem of instantaneously interpreting information. This leads to strategies of launch on warning (fire off the missiles as soon as an attack is perceived, even though it may turn out there is no attack) or launch on attack (wait for a warhead to go off, then send the missiles), both of which put us on a hair trigger. Add to this the 75 pages or so of options in the black book that follows the president around and which no president could understand without repeated briefings and rehearsals. (Only Jimmy Carter showed an interest.) The alternative to this picture of confusion is to strike first. The system for a president to authorize a first strike is fairly straightforward, entailing a computerized attack plan aimed at the Soviet leadership (on the assumption that the highly centralized Soviet system would be incapable of mounting a response). Soviet retaliatory potential is even less than ours, partly because of shoddier technology and partly because the Soviets have paid less attention to it. It is part of our current Single Integrated Operational Plan (SLOP), our plan for nuclear war, to strike first; and the Soviets, knowing they are vulnerable, are encouraged to strike first themselves. The net result: we are really getting close to big trouble. Ford believes that most top brass are more interested in interservice rivalry and acquisitions than in war; but the kind of stuff they're acquiring, including the MX, is moving us steadily toward a first strike. Though both the SlOP and the communications and control angles have been dealt with before, Ford brings them together deftly and with economy. This should be read, but not before going to sleep.