Can thermonuclear war be set off by accident?
What steps have been taken to guard against the one sort of mishap that could trigger the destruction of continents?
Are we as safe as we should be from such a disaster?
Is anything being done to increase our margin of safety?
Will the danger increase or decrease?

I have just asked these questions in the Pentagon, in the White House, in offices of key scientists across the country and aboard the submarines that prowl for months underwater, with neat rows of green launch tubes which contain Polaris missiles and which are affectionately known as "Sherwood Forest".
I asked the same questions inside the launch-control rooms of an Atlas missile base in Wyoming, where officers who wear sidearms are manning the "commit buttons" that could start a war -- accidentally or by design -- and in the command centers where other pistol-packing men could give orders to push such buttons.

To the men in the instrument-jammed bomber cockpits, submarine compartments and the antiseptic, windowless rooms that would be the foxholes of tomorrow's impersonal intercontinental wars, the questions seem farfetched.
There is unceasing pressure, but its sources are immediate.
"Readiness exercises" are almost continuous.
Each could be the real thing.

In the command centers there are special clocks ready to tick off the minutes elapsed since "E hour".
"E" stands for "execution" -- the moment a "go order" would unleash an American nuclear strike.
There is little time for the men in the command centers to reflect about the implications of these clocks.
They are preoccupied riding herd on control panels, switches, flashing colored lights on pale green or gray consoles that look like business machines.
They know little about their machinery beyond mechanical details.
Accidental war is so sensitive a subject that most of the people who could become directly involved in one are told just enough so they can perform their portions of incredibly complex tasks.

Among the policy makers, generals, physicists, psychologists and others charged with controlling the actions of the button pushers and their "hardware", the answers to my questions varied partly according to a man's flair for what the professionals in this field call "scenarios".
As an Air Force psychiatrist put it: "You can't have dry runs on this one".
The experts are thus forced to hypothesize sequences of events that have never occurred, probably never will -- but possibly might.
Only one rule prevailed in my conversations with these men: The more highly placed they are -- that is, the more they know -- the more concerned they have become.

Already accidental war is a silent guest at the discussions within the Kennedy Administration about the urgency of disarmament and nearly all other questions of national security.
Only recently new "holes" were discovered in our safety measures, and a search is now on for more.
Work is under way to see whether new restraining devices should be installed on all nuclear weapons.

Meanwhile, the experts speak of wars triggered by "false pre-emption", "escalation", "unauthorized behavior" and other terms that will be discussed in this report.
They inhabit a secret world centered on "go codes" and "gold phones".
Their conversations were, almost invariably, accompanied by the same gestures -- arms and pointed forefingers darting toward each other in arclike semicircular motions.
One arm represented our bombers and missiles, the other arm "theirs".
Yet implicit in each movement was the death of millions, perhaps hundreds of millions, perhaps you and me -- and the experts.

These men are not callous.
It is their job to think about the unthinkable.
Unanimously they believe that the world would become a safer place if more of us -- and more Russians and Communist Chinese, too -- thought about accidental war.

The first systematic thinking about this Pandora's box within Pandora's boxes was done four years ago by Fred Ikle, a frail, meek-mannered Swiss-born sociologist.
He was, and is, with the RAND Corporation, a nonprofit pool of thinkers financed by the U.S. Air Force.
His investigations made him the Paul Revere of accidental war, and safety procedures were enormously increased.

In recent weeks, as a result of a sweeping defense policy reappraisal by the Kennedy Administration, basic United States strategy has been modified -- and large new sums allocated -- to meet the accidental-war danger and to reduce it as quickly as possible.

The chain starts at BMEWS (Ballistic Missile Early Warning System) in Thule, Greenland.
Its radar screens would register Soviet missiles shortly after they are launched against the United States.
BMEWS intelligence is simultaneously flashed to NORAD (North American Air Defense Command) in Colorado Springs, Colorado, for interpretation;
to the SAC command and control post, forty-five feet below the ground at Offutt Air Force Base, near Omaha, Nebraska;
to the Joint War Room of the Joint Chiefs of Staff in the Pentagon and to the President.

Telephones, Teletypes, several kinds of radio systems and, in some cases, television, link all vital points.
Alternate locations exist for all key command centers.
For last-ditch emergencies SAC has alternate command posts on KC-135 jet tankers.
Multiple circuits, routings and frequencies make the chain as unbreakable as possible.

The same principle of "redundancy" applies to all communications on these special networks.
And no messages can be transmitted on these circuits until senders and receivers authenticate in advance, by special codes, that the messages actually come from their purported sources.
Additional codes can be used to challenge and counterchallenge the authentications.

Only the President is permitted to authorize the use of nuclear weapons.
That's the law.
But what if somebody decides to break it?
The President cannot personally remove the safety devices from every nuclear trigger.
He makes the momentous decision.
Hundreds of men are required to pass the word to the button pushers and to push the buttons.
What if one or more of them turn irrational or suddenly, coolly, decide to clobber the Russians?
What if the President himself, in the language of the military, "goes ape"?
Or singlehandedly decided to reverse national policy and hit the Soviets without provocation?

Nobody can be absolutely certain of the answers.
However, the system is designed, ingeniously and hopefully, so that no one man could initiate a thermonuclear war.

Even the President cannot pick up his telephone and give a "go" order.
Even he does not know the one signal for a nuclear strike -- the "go code".
In an emergency he would receive available intelligence on the "gold-phone circuit".
A system of "gold" -- actually yellow -- phones connects him with the offices and action stations of the Secretary of Defense, the Joint Chiefs of Staff, the SAC commander and other key men.
All can be connected with the gold circuit from their homes.
All could help the President make his decision.
The talk would not be in code, but neither would it ramble.
Vital questions would be quickly answered according to a preprepared agenda.
Officers who participate in the continual practice drills assured me that the President's decision could be made and announced on the gold circuit within minutes after the first flash from Aj.

If communications work, his decision would be instantly known in all command posts that would originate the actual go order.
For these centers, too, are on the gold circuit.
They include the Navy's Atlantic Command at Norfolk, Virginia, which is in contact with the Polaris subs;
NATO headquarters in Europe;
Air Force forward headquarters in Europe and in the Pacific, which control tactical fighters on ships and land bases;
and SAC, which controls long-range bombers and Atlas missiles.

Let us look in on one of these nerve centers -- SAC at Omaha -- and see what must still happen before a wing of B-52 bombers could drop their Aj.

In a word, plenty.
The key man almost certainly would be Col. William W. Wisman, SAC's senior controller.
He or his deputy or one of their seven assistants, all full colonels, mans the heart of the command post twenty-four hours a day.
It is a quiet but impressive room -- 140 feet long, thirty-nine feet wide, twenty-one feet high.
Movable panels of floor-to-ceiling maps and charts are crammed with intelligence information.
And Bill Wisman, forty-three, a farmer's son from Beallsville, Ohio, is a quiet but impressive man.
His eyes are steady anchors of the deepest brown.
His movements and speech are precise, clear and quick.
No question ruffles him or causes him to hesitate.

Wisman, who has had the chief controller's job for four years, calls the signals for a team operating three rows of dull-gray consoles studded with lights, switches and buttons.
At least a dozen men, some armed, are never far away from him.
In front of him is a gold phone.
In emergencies the SAC commander, Gen. Thomas Power, or his deputies and their staff would occupy a balcony that stretches across the length of the room above Wisman and his staff.
At General Power's seat in the balcony there is also a gold phone.
General Power would participate in the decision making.
Wisman, below, would listen in and act.
His consoles can give him instant contact with more than seventy bases around the world and with every SAC aircraft.

He need only pick up one of the two red telephone receivers at his extreme left, right next to the big red button marked alert.
(There are two receivers in case one should be dropped and damaged.
)

But Wisman, too, does not know the go code.
He must take it from "the red box".
In point of fact, this is a beige box with a bright red door, about one and a half feet square and hung from the wall about six feet from the door to Wisman's right.
The box is internally wired so the door can never be opened without setting off a screeching klaxon ("It's real obnoxious").

Now we must become vague, for we are approaching one of the nation's most guarded secrets.
The codes in the red box -- there are several of them covering various contingencies -- are contained in a sealed X-ray-proof "unique device".
They are supplied, a batch at a time, by a secret source and are continually changed by Wisman or his staff, at random intervals.

But even the contents of Wisman's box cannot start a war.
They are mere fragments, just one portion of preprepared messages.
What these fragments are and how they activate the go order may not be revealed.
The pieces must be placed in the context of the prepared messages by Wisman's staff.
In addition to the authentication and acknowledgment procedures which precede and follow the sending of the go messages, again in special codes, each message also contains an "internal authenticator", another specific signal to convince the recipient that he is getting the real thing.

I asked Wisman what would happen if he broke out the go codes and tried to start transmitting one.
"I'd wind up full of bullet holes", he said, and there was no question that he was talking about bullets fired by his coworkers.

Now let us imagine a wing of B-52's, on alert near their "positive control (or fail-safe) points", the spots on the map, many miles from Soviet territory, beyond which they are forbidden to fly without specific orders to proceed to their targets.
They, too, have fragments of the go code with them.
As Wisman put it, "They have separate pieces of the pie, and we have the whole pie.
Once we send out the whole pie, they can put their pieces into it.
Unless we send out the whole pie, their pieces mean nothing".
Why does Wisman's ever-changing code always mesh with the fragments in possession of the button pushers?
The answer is a cryptographic secret.
At any rate, three men out of a six-man B-52 crew are required to copy down Wisman's go-to-war message.
Each must match Wisman's "pie" with the fragment that he carries with him.
All three must compare notes and agree to "go".

After that, it requires several minutes of concentrated work, including six separate and deliberate actions by a minimum of three men sitting at three separate stations in a bomber, each with another man beside him to help, for an armed bomb to be released.
Unless all gadgets are properly operated -- and the wires and seals from the handles removed first -- no damage can be done.