PM Files
Report by the Special Committee of the
National Security Council to the President
1
top secret
[Washington,] January 31, 1950.
Development of Thermonuclear Weapons
the problem
1. By letter to Mr. Souers dated November 19, 1949, the President designated
the Secretary of State, the Secretary of Defense, and the Chairman of the
Atomic Energy Commission as a special Committee of the National Security
Council to make recommendations
-
a.
- “as to whether and in what manner the United States should
undertake the development and possible production of ‘super’ atomic
weapons”, and
-
b.
- “as to whether and when any publicity should be given to this
matter.”
analysis
2. The nature of the decision on which the Committee has been called upon to
make recommendations needs to be defined with some precision. Systematic
theoretical investigations on the possibilities of a thermonuclear weapon
were undertaken at Los Alamos in the fall of 1943, and some work on this
problem has been going on since that time (Appendix A).2 …
Assuming a continuation of the present [Page 514] program at the present rate, however, it would be many
years before a test of a thermonuclear weapon would be possible.
The question presented is whether the United States should undertake at this
time an accelerated program to determine the feasibility of a thermonuclear
weapon, should continue its research at the present rate, or should place a
moratorium on further work in this field.
3. An all-out effort leading to both a feasibility test and quantity
production of “supers” would seriously impair the efficiency and output of
the fission bomb program, but there appear to be no advocates for this type
of effort. Technical studies of the Atomic Energy Commission indicate that
an accelerated research and development program to test the feasibility of
such a weapon (as distinguished from a quantity production program) would
require a minimum time of three years; that with such a target date other
weapon developments now under way, principally lighter and smaller weapons
aimed at improved deliverability … could probably still be carried out, but
not with the care and refinement originally planned; that this probable
decrease in refinement would not be sufficiently important to serve as a
deterrent to an accelerated effort on thermonuclear research and development
(Appendix B).3 The
important consideration from a military point of view appears to be that the
most advantageous rate and scale of effort would be such as to produce a
weapon for testing as soon as possible without significant impairment to the
quantity output of fission weapons as scheduled (Appendix C).
4. In the present state of knowledge, it appears that there is at least a
50–50 chance that a thermonuclear weapon will be feasible, but this cannot
be determined except by actual test (Appendix B, par. 1 and par. 17).
5. It is estimated on the basis of technical studies made by the Atomic
Energy Commission and the Department of Defense that an accelerated program,
including ordnance and carrier development, is within the capabilities of
the United States from the point of view of money, materials, and industrial
effort.
6. Knowledge as to whether the thermonuclear bomb is or is not feasible and
knowledge as to its potentialities and limitations, if feasible, are of
importance to military planning and foreign policy planning (see Appendix
C). It should be recognized, however, that the failure of any given test may
not conclusively demonstrate that other methods might not be feasible.
7. It must be considered whether a decision to proceed with a [Page 515] program directed toward determining
feasibility prejudices the more fundamental decisions (a) as to whether, in the event that a test of a thermonuclear
weapon proves successful, such weapons should be stockpiled, or (b) if stockpiled, the conditions under which they
might be used in war. If a test of a thermonuclear weapon proves successful,
the pressures to produce and stockpile such weapons to be held for the same
purposes for which fission bombs are then being held will be greatly
increased. The question of use policy can be adequately assessed only as a
part of a general reexamination of this country’s strategic plans and its
objectives in peace and war. Such reexamination would need to consider
national policy not only with respect to possible thermonuclear weapons, but
also with respect to fission weapons—viewed in the light of the probable
fission bomb capability and the possible thermonuclear bomb capability of
the Soviet Union. The moral, psychological, and political questions involved
in this problem would need to be taken into account and be given due weight.
The outcome of this reexamination would have a crucial bearing on the
further question as to whether there should be a revision in the nature of
the agreements, including the international control of atomic energy, which
we have been seeking to reach with the U.S.S.R.
8. There is evidence which leads to the belief that the Soviet Union prefers
to put its chief reliance on winning the cold war rather than precipitating
a hot war. There is also ground for the belief that the Soviet Union would
prefer not to use weapons of mass destruction except in the event of prior
use by others. These assumptions might appear to argue for renunciation by
the United States of work in the field of thermonuclear weapons. We cannot
safely assume, however, that these hypotheses are correct. Even if they are
correct, it cannot be assumed that the Soviet Union would forego development
of this weapon any more than she has been willing to forego the development
of the fission bomb. Sole possession by the Soviet Union of this weapon
would cause severe damage not only to our military posture but to our
foreign policy position.
9. There is also the question of possible effect on Soviet attitudes and
actions of a decision to proceed with a program to test the feasibility of
thermonuclear weapons.
a. Would a decision on the part of the United States
to go ahead with an accelerated program cause the Soviet Union to press
ahead in this field more vigorously? The theoretical possibilities of a
thermonuclear reaction have long been known; as early as 1932 there were
suggestions by Russian scientists and others that thermonuclear reactions
might release enormous amounts of energy (Appendix A). The [Page 516] Soviet Union probably has felt it could not
make any other assumption than that the United States is working on such a
weapon, especially in view of the public discussion that has already taken
place. It is difficult to escape the conclusion that the Soviet Union will
make an intensive effort to produce thermonuclear weapons. A decision to
accelerate our program may cause the Soviet Union to increase the priority
of these efforts. Knowledge by the U.S.S.R. that we had successfully
completed development of a thermonuclear weapon might have the effect of
increasing the probability that the USSR would successfully develop a
similar weapon. These are risks which are difficult to measure, but which we
must frankly face up to if a decision is made to accelerate our development
program.
b. It does not appear likely that the character of
United States military developments will have a decisive effect on Soviet
military developments or be the cause of an arms race. The Soviet decision
to reequip its armies and devote major energies to developing war potential,
after the end of the war and at a time when we were disbanding our armies,
was based on considerations more profound than our possession of the atomic
weapon.
10. a. The possibility of the Russians’ developing a
thermonuclear weapons capability, added to their probable growing fission
bomb capability, re-emphasizes the importance of effective international
control of the entire field of atomic energy. Even if we can find a new
approach to the control of atomic energy which would be acceptable to us and
to our allies, and which offers greater prospect than the U.N. plan of being
negotiable with Russia, the necessary negotiations probably could not be
completed in less than a year and a half to two years. But to delay an
accelerated program of development for such a period in the absence of
adequate assurance that work in the Soviet Union had been similarly delayed,
would measurably increase the prospect of prior Soviet possession of
thermonuclear weapons.
b. It has been suggested that a decision should be
deferred until an approach has been made to the Soviet Union proposing that
both nations forego work in the field of thermonuclear weapons. If such a
proposal were coupled with a plan for the necessary safeguards to insure
that the renunciation was in fact being carried out—these safeguards
necessarily involving an opening up of Soviet territory—it is the view of
the Department of State that the proposition would be unacceptable to the
Soviet Union to the same degree that the United Nations plan for the control
of atomic energy is unacceptable. If not coupled with such safeguards, it is
not believed that sufficient assurance would be gained from such an
agreement to make it worth while.
[Page 517]
recommendations
11. In the light of the foregoing considerations, the following
recommendations are made:
-
a.
- That the President direct the Atomic Energy Commission to proceed
to determine the technical feasibility of a thermonuclear weapon,
the scale and rate of effort to be determined jointly by the Atomic
Energy Commission and the Department of Defense; and that the
necessary ordnance developments and carrier program be undertaken
concurrently;
-
b.
- That the President direct the Secretary of State and the Secretary
of Defense to undertake a reexamination of our objectives in peace
and war and of the effect of these objectives on our strategic
plans, in the light of the probable fission bomb capability and
possible thermonuclear bomb capability of the Soviet Union;4
-
c.
- That the President indicate publicly the intention of this
Government to continue work to determine the feasibility of a
thermonuclear weapon, and that no further official information on it
be made public without the approval of the President.
[Here follow Appendix A, a historical statement, and Appendix B, a staff
study, prepared by the U.S. Atomic Energy Commission.]
Appendix “C”
The Military Implications of Thermonuclear
Weapons5
the problem
1. To determine the military implications of weapons employing
thermonuclear reactions in deuterium and tritium to obtain energy
releases in the order of millions of tons of TNT.
assumptions
2. That it is within the capabilities of the United States from the
standpoint of money, materials and industrial effort to develop for test
of feasibility a prototype thermonuclear weapon.
3. If the thermonuclear reaction of light elements were proved feasible
of attainment, that it would be within the capabilities of the United
States to produce these weapons in limited quantities.
4. That no practical factors are known to exist which conclusively
eliminate the possibility or probability of Soviet development of a
thermonuclear weapon in minimum quantities.
[Page 518]
5. That moral considerations are not germane to the limited objective
covered by this problem, i.e., the development and test of the weapon to
determine its feasibility. Determination of production and use of the
weapon is likewise outside the province of this problem.
discussion
6. See Annex 1.
conclusions
7. The United States military position with respect to the development of
the thermonuclear weapon should be:
-
a.
- Possession of a thermonuclear weapon by the USSR without such
possession by the United States would constitute a situation
fraught with danger to the United States, and must be
avoided.
-
b.
- It is imperative to determine the feasibility of a
thermonuclear explosion, and its characteristics, at the
earliest practicable date. This determination is essential for
United States offensive and defensive planning, and direction of
research and development.
-
c.
- If a thermonuclear weapon is determined to be feasible, the
following considerations pertaining to military requirements are
currently evident:
- (1)
- Possession of such weapons by the United States may
act as a deterrent to war.
- (2)
- Possession of such weapons by the United States will
provide an offensive weapon of the greatest known power
possibilities thereby providing increased flexibility
and effectiveness to our operations in the event of
hostilities.
-
d.
- The cost in money for materials, and the research and
industrial effort of this determination of feasibility is
estimated at between 100 and 200 million dollars by the Atomic
Energy Commission. This is within the capabilities of the United
States. The USSR has the same capability.
-
e.
- When used against especially selected remunerative targets the
thermonuclear weapon, if feasible, can be utilized in lieu of a
greater number of fission bombs. This would enable the delivery
of a given amount of damage in less time with less exposure and
with greater effectiveness than through the employment of a
greater number of fission bombs. Furthermore, the weapon
promises to be more efficient in utilization of available ore
and production capacity per unit area of damage.
-
f.
- A unilateral decision on the part of the United States not to
develop a thermonuclear weapon will not prevent the development
of such a weapon elsewhere.
-
g.
- It should be possible to maintain the necessary military
secrecy on a subject of such importance to the security of the
United States. However, it is believed that development of this
weapon as a complete surprise to the USSR is not
possible.
-
h.
- In summary, from the military point of view, determination of
the technical feasibility of the thermonuclear explosion is
essential. This does not imply a “crash” or “all-out” program,
but, on the contrary, an orderly and economical solution of the
problem.
[Page 519]
Annex 1
discussion
1. General. From the discussion of technical
considerations by the Atomic Energy Commission, it appears that there is
a reasonable chance that a thermonuclear reaction of light elements can
be achieved by the United States within the next few years after a
special effort in this direction is initiated. Consideration of known
Soviet developments in the field of atomic energy reveals a degree of
Soviet capability also to develop a thermonuclear weapon. The following
discussion explores the implications of the military applications of
thermonuclear weapons in order to present pertinent facts which may be
of assistance in arriving at a decision as to whether or not a special
effort will be initiated at this time to achieve a thermonuclear weapon
or to determine conclusively its lack of feasibility.
2. The Potential Military Applications of the
Super.
a. Effects.
From the point of view of military usefulness, the only effects which
need be given consideration at this time are the blast and thermal
radiation. In contrast to fission bombs, the nuclear radiation will be
relatively unimportant and for the present need only be considered from
a defensive point of view or under special conditions of detonation.
Preliminary studies based on a comparative analysis of effects of a
40,000 KT Super to a 40 KT fission bomb indicate that:
- (1)
- The Super will produce a blast damage area greater than 50
times that produced by a fission bomb.
- (2)
- Under average atmospheric conditions, the Super will produce
thermal effects over an area 60–170 times that from a fission
bomb.
b. Damage Characteristics of the Super.
While the fission bomb may yield an overpressure of 28 p.s.i. or more out
to a distance of 2500 feet, the same pressure level may extend to 23,000
feet in the case of the Super. But there is no comparison between the
destructive level which is attained inside these radii; for the super
pressure levels near “ground zero” are at least twenty times higher than
those for the fission bomb, and the Super bomb pressure level is always
higher than the fission bomb pressure level at corresponding points
inside the two damage circles. Hence, the damage in the large circle
associated with the Super is many-fold more complete than that in the
smaller circle associated with the fission bomb. It must be concluded,
then, that the Super is not directly comparable to a given number of
fission bombs, for the peak pressures attained from the Super cannot be
attained with the airburst fission bombs and these Super bomb pressures
result in complete demolition of a large area.
[Page 520]
Preliminary target studies based on the anticipated effects of the Super
have borne out this conclusion. From these studies it appears that a
limited number of strategic and tactical targets will exist, in the
event of hostilities with the USSR, which are peculiarly adapted to the
Super. The estimated effects of the Super on heavy materiel and
structures and on troop concentrations will permit:
- (1)
- The achievement of certain strategic and tactical objectives
at a substantial saving in terms of fission bombs, one Super
replacing 10–50 fission bombs, depending on the specific
target.
- (2)
- A far higher level of assurance of success against certain
strategic and tactical targets of the highest importance.
- (3)
- The accomplishment of a level of destruction against very
heavy structures, troop concentrations, and materiel which,
though desirable, is not practicable of attainment with fission
bombs except by heavy expenditure and accurate placement on
target.
3. Delivery Considerations. The violence of the
blast and thermal effects of the Super require any manned aircraft to be
a minimum of 30 miles from the detonation point. This requirement will
dictate an unmanned vehicle to traverse the final 50 to 100 miles to the
target. The development of such a vehicle is a problem which remains to
be solved in conjunction with the development of the weapon itself,
being dependent largely upon the characteristics, physical dimensions
and weight of the weapon. It is impracticable at this time to anticipate
the exact nature of the eventual carrier. It is apparent that eventually
a supersonic unmanned vehicle will be necessary, depending upon the
scientific advancement in the field of guided missile ground-to-air
weapons. It is also apparent that under such conditions of opposition, a
supersonic delivery vehicle is also indicated for fission bombs. Thus a
seemingly paradoxical situation may eventually develop wherein the
larger, more cumbersome Super may eventually be easier to deliver by
virtue of the fact that it may be less demanding for refinements in the
guidance system of the final delivery missile. In any event, in
consideration of the technical problems in the development of the weapon
as compared to the carrier, it is believed that the carrier problem,
although difficult, is the lesser of the two.
4. Other Important Military Implications. In
consideration of the above military applications for the Super, the
potential advantages of which would accrue to a nation possessing these
weapons, the following discussion explores additional military
implications under several hypotheses of possession.
-
a.
-
Hypothesis: Sole Possession by the USSR.
Aside from the power ratio differential of the Super as compared
to the fission weapon and of the psychological potential which
automatically exists through enemy exploitation of this ratio
differential, there is the added factor that if we fail to
develop a thermonuclear weapon and thereby lack [Page 521] knowledge of its positive effects,
we shall be unable to counter possible enemy exploitation of the
frightening and paralyzing fiction which has become associated
from time to time with thermonuclear explosions. Accordingly, it
must be anticipated that the development of a thermonuclear
weapon by the USSR in advance of the United States, particularly
if the announcement follows secret development, would have a
demoralizing effect on the American people. It would have
psychological and political repercussions which might raise a
question concerning the continued unity of spirit, confidence
and determination among the nations of the western world. The
situation today is strikingly parallel to that of a few years
ago when this nation was engaged in a race to develop a fission
bomb before Germany. From the Soviet point of view, sole
possession of the thermonuclear weapon would place in their
hands an offensive weapon of the greatest known power
possibilities. It would provide the Soviet leaders, people and
satellites with a psychological boost which in peacetime could
lead to increased truculence in international affairs and
increased political infiltration in nations of the western
world. The “blackmail” potential of the thermonuclear weapon
would serve the USSR well in its aims to impose its will upon
the nations of Europe and to alienate these nations from the
Western camp. In time of war, sole possession of the
thermonuclear weapon and possession of fission weapons coupled
with superiority of conventional military forces would provide
the Soviets with the necessary balance to current Western unity
and to our superior fission weapon stockpile to enable them to
risk hostilities for the rapid achievement of their objectives.
The above developments cannot be forecast with certainty;
however, the materialization of one or more of these possible
developments could have such an unacceptable effect upon our
world position as to force a complete re-evaluation of our
strategic plans and of our national objectives in peace and in
war. It is concluded that possession of a thermonuclear weapon
by the USSR without such possession by the United States would
constitute a situation fraught with danger to the United States,
and must be avoided.
-
b.
-
Hypothesis: Sole Possession by the United
States. The sole possession of this weapon by the
United States would cause all of the practical and many of the
psychological advantages of possession of thermonuclear weapons
to accrue to our side, and may act as a deterrent to war. From
the practical point of view, possession of this weapon would add
materially to the striking power of our forces against those
important tactical and strategic objectives which are
particularly adapted to a thermonuclear weapon. For example,
large concentrations of enemy troops and materiel, such as occur
frequently in war (the Normandy invasion, the defense of
Stalingrad, the Bulge break-through, large dumps, singularly
important airplane concentrations, and other such large but
lucrative targets) which would now require multiple delivery of
fission weapons, could be destroyed or critically disrupted with
a single thermonuclear weapon. Since this destruction could be
applied throughout the target area with simultaneity, the value
of surprise could be exploited to the maximum. Effective
destruction of the above target types may well lead to decisive
results since such concentrations normally occur in connection
with critical operations in war. Moreover, attack of enemy
atomic air [Page 522] bases with
a thermonuclear weapon may be the only effective defense against
enemy atomic attack. If, on the other hand, enemy knowledge of
our possession of this weapon causes them so to conduct
operations as to avoid concentrations of troops and materiel to
a materially greater extent than is now indicated by our
possession of fission weapons, we shall have forced them to
abandon the source of their greatest strength, employment of
mass. There is an additional advantage of the thermonuclear
weapon. The thermonuclear weapon promises in the high ranges of
energy release to be more efficient in the utilization of
available ore and production capacity per unit of damage
area.
-
c.
-
Hypothesis: Possession by Both Countries.
It is clear that under these conditions the world would be
precipitated into the atomic age much more rapidly than would
otherwise be the case. Such requirements as dispersal of
industry, dispersal on the battlefield, avoidance of reliance
upon ports, beachheads, large airfields, etc., would become more
mandatory and on a considerably larger scale than is now
indicated by mutual possession of fission weapons. Under such
conditions it can be anticipated that great stress will be
placed by each protagonist on the attempt to deliver as the
initial act of hostilities a paralyzing blow on the offensive
atomic capabilities of the enemy, such as air bases for the
atomic carrier force. Accordingly, it appears reasonable to
forecast that great effort must be made to allow the development
of suitable techniques of operational employment under
conditions of dispersion which will achieve an adequate degree
of invulnerability of retaliatory attack force.
-
d.
-
Hypothesis: Firm Determination of
Infeasibility. Because of the above military
implications which are associated with the development of a
thermonuclear weapon, it is imperative to determine conclusively
the feasibility of a thermonuclear explosion and its
characteristics. Such determination is essential for United
States defense planning, preparations for retaliation, and
direction for our research and development programs. There are
undoubtedly a number of possible social, psychological and moral
objections which may be considered to argue against research and
development by the United States leading to the development and
test of a thermonuclear weapon. The above considerations
outweigh such objections. In addition, it is difficult to escape
the conviction that in war it is folly to argue whether one
weapon is more immoral than another. The United States has
enjoyed and relied upon a measure of technological advantage
over the USSR. This advantage lies principally in our industrial
capacity, our stockpile of atomic weapons, and our ability to
deliver these weapons. We no longer have a monopoly of atomic
weapons, which fact lessens our degree of technological
advantage. There are indications that the USSR also has some
capability of producing a thermonuclear weapon. To stop
arbitrarily our atomic research at the frontier of thermonuclear
reactions would guarantee the loss of our technological
advantage and further would not prevent development of this
weapon by the USSR as long as war remains a possibility. If we
do not determine the feasibility of a thermonuclear weapon
before a war, we would be forced to make this determination on a
“crash” basis upon the initiation of hostilities. In view of the
above, it is considered that the cost involved in a
determination of feasibility of a thermonuclear explosion [Page 523] is insignificant when
compared with the urgency to determine more accurately the
ceiling on atomic development.
5. Consideration of Current Policy on International
Control. The military is in strong support of the United States
position in the United Nations on international control of atomic
energy. Preliminary studies indicate that the possible existence of a
thermonuclear weapon does not appear to warrant change of the attitude
of the military, with the exception that serious consideration must be
given to the probability that adequate control would be more difficult
and that successful violation of control would be much more significant.
Detailed studies by the United States in this regard are indicated and
should be undertaken without delay.
6. Considerations of Timing and Intensity of
Effort. The overriding considerations which indicate a
necessity for the development and test of a thermonuclear weapon occur
in conjunction with the analysis of the situation which would exist if
the USSR had sole possession of a thermonuclear weapon. Accordingly, our
plans must be on such a scale that we do not lose an appreciable amount
of time in determining the feasibility of such a weapon. From the
military point of view the following minimum program should be
undertaken at this time:
-
a.
- The determination of the technical feasibility of a
thermonuclear explosion as a matter of top priority.
-
b.
- Studies of the necessary delivery vehicle and ordnance
problems should proceed concurrently with a above and should not necessarily await trial of a
thermonuclear assembly.
7: Considerations Regarding Security. There are
many facets to the question of whether it should be made a matter of
public knowledge that the United States is engaged in an active effort
to develop a thermonuclear weapon. It is considered that public
discussion once initiated and encouraged is extremely difficult to
control and inevitably leads to a greater disclosure than originally
intended. An additional factor of military significance is the
divergence of opinion among scientific circles in this country relative
to the feasibility of a thermonuclear explosion. It can be expected that
such divergence of opinion exists in the USSR on at least an equivalent
parity. If the United States announces that we are engaged in an active
effort to develop a thermonuclear weapon, such positive knowledge would
give added credence and ascendancy to the Soviet group sponsoring
development in this field and may result in an earlier start or greater
impetus to the Soviet program. For the above two reasons, it is
considered that any decisions or actions pertaining to United States
effort to develop a thermonuclear weapon or any determination of its
feasibility is military information of the highest security
classification.
