Weaponry: The Folly of the Neutron Bomb

Its proponents call it “humane,” but they disregard the delayed effects of the enhanced radiation warhead, and the likelihood that this weapon would only increase the chances of nuclear war in Europe.


Enhanced radiation warheads—better known as neutron bombs—are low-yield variants of the hydrogen bomb first tested nearly twenty-five years ago. The public disclosure less than a year ago of the development of ERWs has provoked widespread debate, much of it ill-informed, and so it may be in order to review the issues associated with these weapons, which were developed primarily for anti-tank use in Europe.

In 1960 the Atomic Energy Commission’s Livermore weapons laboratory, then led by Edward Teller, was lobbying hard in the Pentagon to establish military requirements for development of “pure radiation” tactical warheads. These were to explode without the help of a fission trigger and therefore were to produce exceedingly little blast and fallout. I was at that time on President Eisenhower’s staff, and I recall a presentation given before a panel of the President’s Science Advisory Committee (PSAC) by an official of the Livermore laboratory, in which he incorrectly said that such a weapon, when exploded above ground, would kill everybody within a certain range but do no grave harm to anybody a little farther away. The Livermore proposal, despite this militarily attractive claim, did not persuade the Administration.

ERWs were discussed again in the mid-sixties when the Sentinel Antiballistic Missile (ABM) Defense System for American cities was being developed by the U.S. Army. The system was to involve, among other components, a short-range Sprint ballistic missile for close-in defense of the cities. This missile was supposed to destroy enemy ballistic missile re-entry vehicles at relatively low altitudes near cities without detonating the large incoming warheads and without damaging the cities. To solve this problem, the AEC’s Los Alamos weapons laboratory turned to an “enhanced radiation” design for the Sprint nuclear warhead and tested this underground in Nevada in the late sixties. Later these warheads were manufactured to equip the Sprints.

Several activist groups attacked the Sentinel system as ineffective, excessively costly, militarily provocative. And the Army’s inept defense of it led to so much public opposition that the project was canceled in 1969.

But the Nixon Administration, without changing the overall design of the system, renamed it Project Safeguard and gave it a new task: the defense of Minuteman ICBM silos against a hypothetical future counterforce attack by Soviet ballistic missiles. Thus camouflaged, the ABM project did squeak through the Senate at budget time in 1969-1970, assisted by the Administration’s argument that the program was needed as a “bargaining chip” in the SALT negotiations. But then came the ABM Treaty, a part of the 1972 SALT I agreements, which restricted each superpower to no more than two ABM installations. In the United States the construction of only one site, near Grand Forks, North Dakota, went ahead. The installation was declared operational in 1974 but was soon ordered mothballed as not cost-effective.

As far as one knows, this $5 billion relic remains inactivated, along with the several dozen Sprint missiles now stored in Army ammunition depots.

Changing emphasis

While Robert McNamara was secretary of defense, the emphasis was strongly on nuclear deterrence through the maintenance of capacity for assured destruction of the enemy. The problems of nuclear battlefield tactics were of secondary interest, and low priority was given to the modernization of tactical nuclear weapons. However, as a part of the modernization of shortrange Army missiles, several nuclear warheads were being developed for the new missile called Lance. One of these was to be of the enhanced radiation type, but it was terminated as not acceptable to the Army.

Under Defense Secretary Melvin Laird, and then under James Schlesinger, the attitude toward tactical nuclear warfare changed. Schlesinger particularly—to judge by his public statements—was interested in the problems of fighting nuclear wars, not just in deterrence. The Army requested funds for modernization of its tactical nuclear weapons without, however, including ERWs. A number of senior Army leaders judged ERWs to be of low battlefield effectiveness. The reason for this skepticism was the finding, based on animal experiments (refuting what we in PSAC were told in 1960), that only within a relatively small area near the explosion would the enemy troops be instantly incapacitated. Troops occupying a much larger area would be injured, though they would remain capable of fighting for at least some time after the irradiation and before death.

These modest warhead modernization plans of the Army were, however, rejected by the Joint Congressional Committee, influenced no doubt by the spokesmen for the AEC weapons laboratories, which were eager to push ahead with nuclear weapons technology. Thus, early in 1973, Harold Agnew, the director of the Los Alamos laboratory, in his testimony before the Joint Committee on Atomic Energy, evidently had ERWs in mind when he stated: “We at Los Alamos are working very aggressively trying to influence the DOD to consider these . . . weapons which could be decisive on a battlefield, yet would limit collateral damage that is usually associated with nuclear weapons.” As a consequence of these political pressures, while James Schlesinger was secretary of defense, the tactical ERWs became a major development project, though the project was transferred from Los Alamos to the Livermore laboratory.

The development of the ERW was a technical success, and late in 1976 President Ford signed an authorization, as required by law, to stockpile the ERWs for the Lance missile and for the shells of 8" artillery guns. This project was highly classified and known to only a few members of Congress.

Hidden items in the budget

The money for the production of ERWs was requested in the fiscal year 1978 budget proposal. ERDA (which succeeded AEC) buried this item among many others in the $10 billion public works section of the President’s budget. No Arms Control Impact Statement was provided to Congress, although it is required by law for new weapons. Altogether, the procedure was unsavory.

What happened next is reconstructed here largely from a series of articles in the Washington Post which began on June 6, 1977.

The review of the Ford budget proposals for fiscal year 1978 by the incoming Carter Administration in early 1977 resulted in the elimination of a $65 million item for the production of nonnuclear warheads. The reason given to Congress was that their use would not be cost-effective, because the Lance missiles, which have a range of about 100 kilometers, depending on the weight of the warhead, were too expensive—about $100,000 each. Another $43 million item, this one for nuclear warheads, was left in the budget, and it appears that neither President Carter nor Secretary of Defense Brown was informed that a new military technology was to be thus introduced into the military arsenal until the following June, when the issue, much against the Pentagon’s wishes, became public.

Near the end of May or in the beginning of June 1977, Senator Mark O. Hatfield, reportedly tipped off by an ERDA official, learned that the budget item for Lance nuclear warheads was for building neutron warheads. Hatfield offered an amendment to the Pentagon’s public works budget bill, then before the Senate Military Appropriations Committee, to strike from the bill the funds for the production of the Lance nuclear warheads. The chairman of the committee, Senator Stennis, opposed the move, and on June 22 the amendment lost on a 10-10 tie vote.

In the meantime the White House issued a statement that President Carter was not bound by Ford’s action and would make an independent decision about the production of ERWs when certain military policy reviews were concluded. Then, in response to an enquiry, the director of defense research and engineering informed Senator Hatfield that the President might not make a decision on the ERW for Lance until the start of the fiscal year 1978 in October, but he urged Congress to appropriate the funds without waiting for this decision.

Congressional maneuvers

Toward the end of June, the House voted the funds for the ERWs. And on July 1, the Senate accepted a Stennis amendment designed to neutralize Hatfield’s amendment, which had been reintroduced on the floor. Then, on July 13, after a message from President Carter that the provision of funds for the production of the new warheads was in the national interest, the Senate, in a day-long and rather bitter debate, approved the public works bill, rejecting Hatfield’s amendment and one of Senator Kennedy’s, which would have allowed either house to block the President’s decision to go ahead with neutron warheads. But it accepted an amendment by Senator Byrd giving Congress forty-five days to pass a concurrent resolution disapproving production of these warheads if the President does decide to go ahead.

As these parliamentary maneuvers were going on, it was revealed that money would be used not only for Lance warheads but to produce enhanced radiation artillery shells for the 8" guns which are now provided with more conventional nuclear warheads. It also became known that the development of ER nuclear projectiles for 155 mm howitzers was under way.

On August 13, 1977, the U.S. Arms Control and Disarmament Agency delivered to Congress the requested Arms Control Impact Statement for the “W-70 Mod 3 (Lance) Warhead.” The statement noted that a one-kiloton ER warhead promised to be as effective as a 10-kiloton fission warhead. With both warheads, radiation is the chief antitank effect, since armored vehicles are highly resistant to blast and thermal effects of nuclear explosions. The statement noted that collateral damage, that is, damage to the civilian environment of the battlefield, would be only that of a one-kiloton weapon, substantially smaller than that of the 10-kiloton fission warhead. No impact statements for the 8" and 155 mm artillery projectiles were released by the ACDA.

In the fall of 1977, President Carter further postponed the decision on the production of ERWs because he desired first to be assured that our NATO allies wished them to be deployed in Europe.

A matter of degree

It has been stated in open literature that the presently deployed “ordinary” nuclear warheads for the Lance missile range in yield from one to as high as 100 kilotons, while those for the 8" guns range up to 10 kilotons. The proposed ER warheads for Lance and the 8" guns are described as of one-kiloton yield, although it is noted in the impact statement that the Lance warhead has a “selectable yield capacity,” and thus may be varied in the field, presumably from less to more than one kiloton.

Because of a substantial contribution from the fission “trigger,” the ERWs are not pure fusion. The Lance warhead, for instance, releases about 60 percent fission and 40 percent fusion energy on explosion, about ten times as much neutron radiation as a pure fission weapon of the same yield.

From the information in the handbooks on effects of nuclear weapons, it is possible to estimate the neutron radiation from ER warheads. The result is not precise, but the uncertainty is not important for what follows.

A one-kiloton ERW explosion produces neutron radiation which in the open causes an exposure of 8000 rad units at a distance of 900 meters (more, of course, at shorter distances). The Soviet tanks are said to have currently a radiation protection factor of 0.5. Thus, tank crews at that distance would receive a dose of around 4000 rads.

According to Pentagon tests with rhesus monkeys, this dose is enough for “immediate transient incapacitation,” which is defined as inducing within five minutes a total inability to perform physically demanding tasks. This is deemed to be an adequate battlefield incapacitation, although partial recovery occurs in about half an hour; then gradual deterioration sets in and death follows two to six days later. At about 700 meters the radiation intensity would be double that at 900, and that exposure, according to the rhesus monkey tests, would result in “immediate permanent incapacitation,” with death agony lasting one or two days.

Walking dead

It has been argued that disciplined military personnel, even though irradiated to the limit of “immediate transient incapacitation,” would resume participation in battle after their partial recovery, perhaps even more recklessly than others, because they would know that they were the walking dead. In any case, tank crews and other military personnel exposed to less radiation than that causing “immediate transient incapacitation” would be able to participate in the battle, although temporarily. Thus, a dose of 650 rads (at about 1400 meters from the one-kiloton ERW) would impair human functions only after an hour or more, though it would usually result in death a couple of weeks later, after a gradual physical decay.

Reliable information on effects of exposure to lower doses of ionizing radiation is available from observations on the survivors of Hiroshima and Nagasaki bombings and on unintended victims of nuclear weapons tests in the Pacific, among the population of the Marshall Islands and the crew of a Japanese fishing vessel.

At a 1.7 kilometer distance from the one-kiloton ERW explosion, the radiation exposure dose drops to 150 rads. Statistically, this results in about 10 percent deaths from radiation sickness within a few months at most, and also in high incidence of breast, thyroid, lung, and stomach cancers as well as leukemia, which may be delayed as much as twenty to thirty years.

At a distance of 2.3 kilometers the exposure drops to 15 rads. This is low enough so that radiation sickness is not experienced after exposure but delayed cancers and leukemia are expected in some of the exposed population.

The harmful genetic effects may manifest themselves for several generations; they also decrease with decreasing exposure. At about 2 kilometers, their frequency would be double the spontaneous rate of mutations, which is statistically quite unmistakable.

The above estimates of the effects of radiation exposure are probably conservative, since they were mostly derived from observation of individuals exposed largely to gamma radiation. The ERWs, however, cause damage by neutrons, and it is well established that high-energy neutrons, per rad of dose, produce about seven times as much biological damage as gamma rays. Thus, for instance, the effects described above as taking place at a 1.7 kilometer distance might actually apply to a 2.1 kilometer distance, and so on.

Considering these facts, it is preposterous to call the neutron bomb humane, as some proponents have done. The area of rapid battle incapacitation of tank crews would be but one fifth of the area of about 4 kilometers in diameter within which the great majority of exposed individuals, military and civilian, would suffer radiation illness and a large fraction would die either from that or years later from cancer. The neutron bomb does not appear to be more humane than the fission warhead, and is perhaps worse, being reminiscent in its delayed effects of the poison gases of World War I, which were outlawed by the Geneva Protocol of 1925.

There is no doubt that collateral damage to civilian structures and persistent radioactive contamination will be reduced if the present higher-yield tactical fission warheads are replaced by ERWs. That the same is true of civilian casualties is quite doubtful for the following reasons.

The Soviet tactical doctrine calls for a large separation between tanks in the nuclear warfare environment, especially when exploiting a breakthrough. If NATO forces deploy ERWs as their prime anti-tank weapon, the Soviets are likely to provide added radiation protection to their tank crews. Furthermore, since exposure to neutron radiation would leave most of the armored vehicles in usable condition, and the battlefield not heavily radioactive from fallout, the attacker could be prepared with replacement crews to return the armored vehicles to battle quickly.

It becomes clear, therefore, that to contain a major blitzkrieg-style breakthrough, involving many armored vehicles, with ERWs—probably their main purpose —will call for large numbers of these weapons, indeed for veritable neutron-bomb barrages. Perhaps the number of prompt deaths of bystander civilians would be modest, but when delayed deaths following radiation sickness (and the incidence of cancer, etc.) are counted in, it ceases to be obvious that the use of ERWs will be much less disastrous to the civilian population in Western Europe, especially in the Federal Republic of Germany, than the use of fission warheads.


The military leaders of NATO, according to the recent testimony of the NATO supreme commander, General A. M. Haig, Jr., before the Senate Armed Services Committee, favor deployment of the ERWs. This, of course, is merely consistent with their traditional emphasis on the recourse to nuclear weapons as the deterrent to an attack by Warsaw Pact forces.

The ACDA impact statement has this to say: “It can be argued that the improved (ER) warhead may make initial use of nuclear weapons in battle seem more credible, which might enhance deterrence. However, by the same token, it can be argued that it increases the likelihood that nuclear weapons would actually be used in combat.” This latter argument has been advanced by several thoughtful opponents of the neutron bomb and is one which must be taken seriously. The reason for deploying ERWs, in the eyes of their proponents, is to enhance the credibility of the initial use of nuclear weapons. But to be effective they would have to be used quite early, and hence ERWs are quite likely to lower the nuclear threshold if NATO forces are attacked. Moreover, as the impact statement notes: “The escalating potential is the same for this weapon as for any other nuclear weapon.” This latter assessment is diametrically opposite to the assertions of some American military writers that the use of ERWs— “mini-nukes” in Secretary Schlesinger’s terminology —would avoid nuclear escalation.

The American opponents of the neutron bomb—and they include almost all those who favor a reduction of tensions by arms control agreements—advance other arguments against the deployment of ERWs in addition to those here discussed. It has been pointed out that the Soviet military doctrine calls for immediate large-scale response with nuclear weapons to any first nuclear use by the NATO forces, and Soviet tactical warheads are estimated to be large and “dirty.” This, of course, totally nullifies the argument about the reduction of collateral damage in Europe by the use of ERWs.

The American armchair strategists have in recent years stressed that a restriction of tactical nuclear weapons to mini-nukes would create a “firebreak” against an escalation to strategic nuclear forces of a tactical nuclear war in Europe. Such decoupling of tactical and strategic nuclear warfares, which of course would protect the American homeland, has been for years a constant theme of American writers favoring tactical nuclear weapons.

West German reaction

Not surprisingly, this thesis finds little support in Western Europe, especially in West Germany, the prime battleground in the event of an attack by Warsaw Pact forces. Thus, in a 1972 report of the West German Defense Ministry to NATO, one finds the statement, “Only by this inseparable connection between tactical and strategic deterrence is NATO capable of equating the conventional [military] superiority of the Warsaw Pact.” And Helmut Schmidt, now the chancellor and then the defense minister of the Federal Republic of Germany, objected to exclusively tactical nuclear warfare as being “unimaginably cruel to the Europeans.”

From the moment that the neutron bomb issue surfaced in Washington, European and especially West German press, media commentators, scholars, and politicians devoted much space and time to it. Conservative papers generally endorsed the deployment of ERWs in West Germany, but moderate and liberal publications opposed it.

On the political level the public debate was triggered by Egon Bahr, executive secretary of the Social Democratic party (SPD) and an influential member in the administration of former Chancellor Brandt, whose article unequivocally condemned the neutron bomb as a “symbol of mental perversion.” Most of the other spokesmen of the SPD opposed ERWs as lowering the nuclear threshold without the assurance of an escalation to strategic levels. A few, such as Conrad Ahlers, tentatively endorsed ERWs last summer, although more recently Ahlers changed his view.

The SPD convention endorsed a resolution urging on the Schmidt government policies which would make neutron bomb deployment on West German territory unnecessary.

The government of Chancellor Schmidt has so far refrained from publicly committing itself, although the defense and foreign ministers have made statements which seem to be in favor of ERW deployment.

Among the political-strategic thinktanks of German academia, only one, led by a retired general, endorsed the deployment of ERWs. Other senior retired German military officers, including high-ranking generals, oppose the battlefield use of nuclear weapons as leading to unacceptable collateral damage in Germany.

In this extensive debate, which shows no signs of ending, another objection to ERWs has been raised, namely that their deployment in large numbers near the forward NATO defense lines may result in a loss of control by the President of the United States and political leaders of NATO over the initiation of nuclear warfare. It has been pointed out that just such concern a decade ago induced the American withdrawal from Europe of the original mini-nuke, the Davy Crockett anti-tank infantry weapon.

It has also been argued that extensive deployment of ERWs may actually induce a pre-emptive nuclear strike by the Soviet Union. This would start nuclear warfare on terms disastrous to NATO forces.

Soviet pressures

In the rest of Western Europe the neutron bomb has been a less important issue. The governments of NATO countries that were queried on their position regarding the deployment of ERWs by Congressman Christopher i Dodd last September gave him “ambivalent responses.” Quite recently, President Brezhnev dispatched letters to the heads of governments of NATO countries warning them against the deployment of ERWs. This intervention was preceded and followed by other forms of protest by the Soviet Union against the neutron bomb. Personal messages from Brezhnev were interpreted as pressure: they produced the normal negative reaction in the West, and may work toward the adoption of the ERWs.

It would appear that if our allies, especially West Germany, should recommend to President Carter the production and deployment of ERWs, they will do so against a significant domestic opposition. In fact, the Dutch parliament voted in March its opposition to the deployment of ERWs in Europe.

Exposed to these conflicting pressures—military clamoring for the neutron bomb, civilian spokesmen largely opposed to it—the NATO governments did not respond affirmatively to Carter’s stipulation last fall that they must endorse deployment of ERWs in Europe before he would order their production. An impasse resulted.

As President Carter left on his April trip to South America and Africa, the New York Times, which editorially had endorsed the deployment of the ERWs, published a story that Carter, without informing our NATO allies, had decided to terminate the ERW project. This apparent double cross naturally created quite an uproar in NATO official circles. President Carter was put into difficult position, and on April 7 he announced that the project was by no means canceled. However, production is indefinitely postponed, and will be reconsidered in the light of future decisions by the Soviet Union regarding its nuclear deployments facing NATO forces.

But if the ERWs are not deployed, would that signify an inability of the NATO alliance to counter the Warsaw Pact’s military threat? American hardliners regard this threat as enormous and imminent. Thus Frank Barnett, the director of the National Strategy Information Center, wrote: “[The United States] ... is about where Britain was in 1938 with the shadow of Hitler’s Germany darkening all of Europe.” And American military men, including General Haig, paint a fairly grim picture. But the annual report of Secretary of Defense Harold Brown, while recognizing the possibility of a future threat, clearly does not regard it as imminent. And Congressman Les Aspin, a highly qualified analyst of military problems, points out that during the period 1972-1976, the Soviet production of tanks and tactical aircraft, both important indicators, exceeded that required just to maintain level inventories by only a few percent a year—a tiny fraction of the rate of Nazi Germany’s buildup of forces in 1938.

“Precision-guided” munitions

Thus, although the numerical tank superiority of Warsaw Pact forces is unquestionable, the severity of the threat this poses is in dispute. Most important in this regard is the record of the 1973 Arab-Israeli war, which showed that modern tanks are very vulnerable to the non-nuclear, hightechnology, “precision-guided” munitions which were then for the first time extensively employed on the battlefield. These munitions find their origins in such early devices as the French wireguided anti-tank rocket of the fifties and the “smart” guided bombs of the late phase of the Vietnam War. The demonstration of the effectiveness of precision-guided munitions against massed tanks in the Middle East has led to intense development of forts. According to the annual report the secretary of defense, American forces in Europe already deploy weapons code-named TOW, DRAGON, and COBRA/TOW, of which it has been said that “what can be seen will be hit and what be hit will be destroyed,” and the “seeing” is done with the aid of infrared, lasers, radar, and so forth. Another important anti-tank role is attributed the guided artillery shell for 155 mm guns, code-named COPPERHEAD. West Germany has deployed a sophisticated anti-tank device code-named MILAN. Our European NATO allies have severother, more advanced, anti-tank weapons ready for final evaluation.

All these developments have led the undersecretary of defense for research and engineering, W. J. Perry, to say: “We can greatly enhance our ability to deter war without having to compete tank for tank, missile for missile, with the Soviet Union.”

Compared to nuclear battlefield weapons, precision-guided munitions are relatively inexpensive. They require, to be sure, larger combat manpower (and its more intensive training) than the mini-nukes, and this is a serious drawback. But they would not place NATO decision-makers in the dangerous position of having either to delay too long in the use of battlefield ERWs or to act prematurely, risking nuclear devastation of Europe and even general nuclear war.

Is there any doubt as to which way an enlightened decision should go?