19. National Security Council Report1

NSC 5515/1


Note by the Executive Secretary to the National Security Council


  • A. NSC Action No. 1260–c
  • B. NSC 5438
  • C. NSC 5515
  • D. NSC Action No. 13662

The National Security Council, the Secretary of the Treasury, the Acting Director, Bureau of the Budget, and Mr. J. Walter Yeagley for the Attorney General, at the 243rd Council meeting on March 31, 1955,3 noted the Study contained in NSC 5515, amended as set forth in NSC Action No. 1366–b, and enclosed herewith as NSC 5515/1.

Because of the sensitivity of the information therein, this Study is being given a limited distribution; it is requested that special security precautions be observed in its handling and that access to it be limited on a strict need-to-know basis.

James S. Lay, Jr.4


Scope of This Study

1. This study, based on a report by a special subcommittee of the NSC Planning Board,5 describes what possible Soviet action or series or group of actions should leave no doubt in the President’s mind as to [Page 72]the need for taking immediate military action to save the United States from the consequences of enemy attack, or to postpone, lessen or prevent imminent enemy attack.

2. For purposes of this study, the term “military action by the U.S.” includes action ranging from lesser measures (such as mobilization, redisposition of U.S. forces, a possible warning to the USSR accompanied by a limited demonstration of force, etc.) all the way to actual hostilities. The study is limited to consideration of the Soviet actions which might be taken; it does not identify the sources or methods by which intelligence or information of such actions might be derived, or identify the precise nature of the military actions (war plans) which might be taken. While refraining from dealing with the nature of U.S. counteraction, the study nevertheless does not imply that the U.S. response should necessarily be uniform in nature. The U.S. response would have to be adapted to the danger to the U.S. inherent in each instance, and might include actions other than military measures.

3. Possible Soviet actions have been examined in terms of their bearing on the imminence and probability of an attack on the U.S. by the USSR. The possibility can not be excluded that certain actions, obviously acts of war, might be undertaken by the USSR without warning, such as a declaration of war on the U.S., a Soviet military attack on the continental U.S., or the detonation of a nuclear weapon in the U.S. However, such acts are outside the scope of this study, the purpose of which is to identify and anticipate Soviet actions preliminary to an attack.

4. Possible Soviet actions preliminary to an attack upon the continental U.S. are listed in the next section of this study under three categories according to the degree of certainty or imminence of such an attack.

5. There is no hard and fast dividing line between the categories of possible Soviet actions. It is probable that Soviet actions enumerated in category I would not occur in isolation from those listed in categories II or III. The impression of simplicity and precision given by the lists which follow should not be allowed to disguise the fact that a difficult and complex value judgment would be involved in determining the exact significance of certain of these actions within the context of the general situation existing at the time of their occurrence.

6. This study can be considered valid only in terms of the current world situation and of Soviet capabilities as set forth in current National Intelligence Estimates. As the world situation and Soviet capabilities develop in the future, the significance of certain of the Soviet actions considered herein will doubtless change. Therefore, this study cannot be viewed either as a long-range or all-inclusive guide.

[Page 73]

7. It is assumed that firm and conclusive evidence that the USSR had decided to undertake any of the actions listed below would be equivalent to the occurrence of the act itself. The order of listing in any category is not necessarily an indication of priority. Moreover, it should be noted that nothing in this study affects the mission of the Watch Committee of the IAC, which is “To provide earliest possible warning to the United States Government of hostile action by the USSR, or its Allies, which endangers the security of the United States.”

Possible Hostile Soviet Actions

8. Although as previously mentioned the possibility of total surprise cannot be excluded, it is considered that Soviet actions immediately threatening the safety of the continental U.S. would probably occur against a background of increased international tension and a drastic change toward an offensive posture by Soviet military forces.

Category I

9. Any of the following specific Soviet actions should be judged in and of itself as clear evidence that Soviet attack upon the continental U.S. is certain or imminent:

Penetration of the continental air control and warning system by Soviet aircraft in a flight pattern indicating attack upon the continental U.S.
Introduction into or possession within the U.S. of a complete nuclear weapon, assembled or unassembled, or of the nuclear components of a nuclear weapon, of Soviet origin or under Soviet direction.
Soviet attacks against U.S. territories (Alaska and Hawaii), U.S. possessions, the Pacific Trust Territory, the Panama Canal Zone, U.S. armed forces or bases overseas.6
Soviet attack against the countries or territories covered by the NATO mutual defense guarantees.
Concentration of Soviet submarines in a postion and in sufficient numbers to permit effective attacks on major U.S. coastal target areas.
Laying of Soviet minefields in approaches to U.S. ports or in coastal shipping routes (an action regarded as unlikely).

Category II

10. Any of the following specific Soviet actions should be judged as clear warning that Soviet attack upon the continental U.S. is probably imminent: [Page 74]

Soviet aircraft in a flight pattern capable of attack upon the continental U.S. detected in the approaches to the continental air control and warning system.
Any concentration of Soviet submarines in the approaches to the continental U.S. coast, particularly if accompanied by the absence of substantial numbers of long-range submarines from their normal stations.
Extensive preparations by the long-range air force for early offensive operations. A few, but by no means all or conclusive, manifestations of such a situation might be (1) movement of key atomic technicians to launching sites, (2) extensive standdowns of long-range air units for maximum maintenance, (3) unusual or increased logistical activities under high priority to launching sites, (4) massing of substantial numbers of long-range air units at forward bases.
Delivery of an ultimatum to the U.S. under threat of attack.
Soviet attack against any of the following: Japan, the Ryukyus, South Korea, Formosa, the Pescadores, the Philippines, Australia, or New Zealand.
Soviet attempts to smuggle weapons of mass destruction into bases abroad where U.S. forces are located or into areas under U.S. jurisdiction outside the continental U.S.
Soviet attempts to introduce into the U.S. or areas under U.S. jurisdiction significant amounts of biological, chemical or radiological warfare agents.
Destruction, or attempted destruction, by Soviet sabotage teams or indigenous communist teams under Soviet instructions of key military or industrial facilities.
Soviet action to assassinate or to attempt to assassinate key U.S. civil and military authorities.

Category III

11. Any of the following specific Soviet actions should be judged as a possible prelude to Soviet attack upon the continental U.S., or as creating a serious international situation which, through action and counteraction, might lead to Soviet attack on the continental U.S.:

Delivery of a Soviet ultimatum, under threat of attack, to a NATO country or Japan, including an ultimatum to remain neutral.
Soviet or East German blockade of West Berlin; Soviet blockade of Vienna.
Soviet attack against Iran.
Soviet attack against Yugoslavia.
Soviet attack against Sweden.
Soviet occupation of Finland.
Soviet active assistance, either by the provision of organized offensive armed forces or nuclear weapons, to Far Eastern communist forces engaged in hostilities against any area covered by a U.S. defense agreement, or area related thereto.
Setting up by Soviet-controlled or communist party-controlled personnel of signal devices for the purpose of directing bombing or guided missile attacks against the U.S., Canada or Mexico.
Organized armed insurrection in the U.S. by communist party members or persons under Soviet direction (an action regarded as unlikely).
Distribution in the U.S. of previously cached weapons, ammunition, explosives, or instruments capable of supporting enemy attack or insurrection, by communist party members or persons under Soviet direction.

  1. Source: Department of State, S/SNSC Files: Lot 63 D 351, NSC 5515 Series. Top Secret.
  2. See footnote 6, supra .
  3. See supra .
  4. Printed from a copy that bears this typed signature.
  5. [Enclosure]
  6. This subcommittee was composed of representatives from four government agencies. The chairman, Jacob D. Beam, represented the Department of State. Colonel Weldon H. Smith, USAF, attended for the Joint Chiefs of Staff; Huntington Sheldon, Assistant Director for Current Intelligence, and his alternate, Dr. Ray S. Cline for the CIA; and Alan H. Belmont, Assistant Director, for the FBI. A copy of the subcommittee’s draft report, submitted to the National Security Council Planning Board on February 28, is in Department of State,PPS Files: Lot 66 D 70, S/P Record Copies Jan.–May, 1955.
  7. The term “attack” as used in this study refers to offensive action undertaken for the purpose of destroying or overwhelming a strategic objective. An “attack” is distinct from a skirmish or armed reconnaissance. [Footnote in the source text.]