In National Security Action Memorandum No. 311 (NSAM 311), President Johnson ordered Secretary of State Dean Rusk, Secretary of Defense Robert McNamara, and Director of Central Intelligence John McCone to review the prospect of a repeat of the Cuban Missile Crisis and to outline the various alternatives that would be available if it happened.
Date: July 10, 1964
Author: McGeorge Bundy
Title: NSAM 311: Review of the Problem of Assurance Against Any Missile Crisis in Cuba
Archival Source: "NSAM 311-Review of the Problem of Assurance Against Any Missile Crisis in Cuba" folder, Box 5, National Security File: NSAM, Lyndon B. Johnson Library
A copy of the some of the findings are available here. Other related documents remain pending declassification review.
July 10, 1964
National Security Action Memorandum No. 311
To: The Secretary of State
The Secretary of Defense
The Director of Central Intelligence
Subject: Review of the problem of assurance against any missile crisis in Cuba
The President has requested that a careful study be made of all aspects of the problem of maintaining adequate assurance against an attempted reintroduction of offensive missiles into Cuba. He requests that this study be undertaken by representatives of the Secretary of State, Secretary of Defense, and the Director of Central Intelligence, with the Senate Department representative as chairman.
This inquiry should assess such questions as (1) the probability and prospect of a renewed Soviet attempt to introduce missiles, (2) the different levels of assurance which might be achieved by various means of obtaining information, (3) the possibility than an increase or decrease in tension with Cuba might change the urgency of the problem or the availability of various means of information, (4) the various kinds of risk which various means of assurance involve, and (5) prospective changes in the "state of the art" of different methods of surveillance.
It is expected that this group will work closely with the United States Intelligence Board, with government agencies involved in research and development, and with those responsible for policy planning. It is requested also that the chairman of the group maintain liaison with my office, through Mr. Peter Jessup with me directly, as he thinks appropriate.
It is not expected that this review group should reach final recommendations, but rather that it should examine all aspects of this question and prepare a report showing as clearly as possible the various courses, with their premises and consequences, which may be available to the U.S. in the future. After a preliminary survey the chairman and I will agree on a completion date for this study.
SUBJECT: Review of the Problem of Assurance Against any Missile Crisis in Cuba (NSAM 311)
1. The Nature of the Problem.
In examining the question of assurance against a possible missile crisis in Cuba, we have analyzed the following component elements of the problem:
a. The minimum essential US requirement for intelligence coverage of Cuba.
b. The likelihood that the Soviets will try to reintroduce and deploy offensive missiles in Cuba.
c. Castro's probable actions with respect to US overflights.
d. Handling of a Cuban complaint in the UN.
e. Alternative US courses of action, and their implications, if the risk of a shoot-down increases.
f. Alternative US courses of action, and their implications, in the event of an actual shoot-down.
2. The Recruitment for US Intelligence Coverage of Cuba.
a. Although other activities within Cuba are of substantial intelligence interest, this paper has been prepared on the precise that the surveillance requirement should be determined solely by the need for timely detection of the presence of offensive missiles in Cuba. In meeting this basic requirement, ancillary intelligence obtained on other activities is regarded only as a bonus.
b. It is our judgment that the minimum surveillance requirement now can most accurately be stated in these terms: in the absence of on-site inspection, the US needs interpretable photography of about 90 per cent of Cuban territory once every four weeks.  "Interpretable photography" in this context means photography that will permit the readout of the presence of offensive missile systems, including MRBMs deployed in field sites. (A more detailed analysis of the requirement is at Annex A.) [USIB paper, 25, November 1964]
3. Likelihood of Reintroduction and Deployment of Offensive Missiles.
a. Since this paper proceeds from the premise that the US surveillance requirement should be focused solely on ensuring the ability to detect evidence of reintroduction and deployment of offensive missiles, an assessment concerning the likelihood of such Soviet action is important. We endorse the recent judgment of the intelligence community (see SNIE 85-3-64, Annex B) that"
(1) The Soviets are unlikely to reintroduce offensive missiles into Cuba in the next year or two, although such an attempt cannot be ruled out;
(2) Events elsewhere, rather than US-Cuban tensions, would probably be the controlling factor in a Soviet-Cuban decision on this issue.
b. Nevertheless, US interests require that we maintain the ability to detect reintroduction and deployment. If our surveillance program were significantly reduced, it is also possible that the Soviets would be somewhat more inclined to believe that a missile deployment could be concealed. On balance, however, we still believe they would now make the attempt.
4. Castro's Challenge.
a. Castro has clearly stated his intention of challenging our U-2 flights over Cuba, and Khrushchev made promises to support this challenge. Castro has indicated that his first move will be in the United Nations; if the UN response is unsatisfactory to them, both Castro and the Soviets (prior to Khrushchev's departure from power) have indicated that a shoot-down of a US reconnaissance plane is contemplated.
b. It is our judgment that a Cuban shoot-down of a U-2 is unlikely in the immediate future, and that it is nost unlikely to come without significant political warning, such as a complaint in the UN.
5. Handling of a Cuban Complaint in the UN.
a. It can be anticipated that Castro will press hard for cessation of US overflights. The US tactic should be to resist Cuban arguments (though the US would of course accept adequate UN inspection arrangements), on the basis that our continuing surveillance grows out of the 1962 missile crisis arrangements and the Cuban refusal to permit on-site inspection. With the changes in circumstances since 1962, however, the Cuban might enlist substantial support for their complaint about infringement of their sovereignty; such support might enholden them to try a shoot-down. The critical element in their decision is likely to be the degree of Soviet support for aggressive Cuban action; our present judgment is that the Soviets are likely to wish to avoid a confrontation with the US over Cuba.
b. If, in exchange for UN surveillance of Cuba, the US were able to offer some reciprocity (e.g. limited UN inspection of Florida ports), Castro's tactical position would be weakened. It is also possible that the USSR would be less inclined to give Castro strong support if the use of force against our aerial surveillance. It is unlikely than an inspection system which would be acceptable to Cuba and to the UN would be as effective as our present surveillance operations. Whether Castro would be tempted to accept the reciprocity proposed is uncertain; it seems likely that minimal US conditions for adequate inspection would be unacceptable from the Cuban viewpoint. Nevertheless, the offer of such an arrangement could strengthen the position of the US in preventing a shoot-down and would provide a basis for justifying the use of force in retaliation for a shoot-down if it did occur.
c. Despite the political advantages of the above tactical approach, it could have the disadvantage of undermining the basic US position in Cuba by tending to equate their rights to inspection (which they do not now have) with our rights to overfly Cuba in lieu of ground inspection (a right we have continued to exercise). The reciprocal inspection proposal would, in our judgment, have adverse domestic political implications. In addition, since Castro would probably also insist upon including Central America within the reciprocal inspection proposal, this could create difficult political problems with Central American nations. (In any event, consultation with the OAS would be essential before the US advanced such a proposal.) Therefore, the US should not initially advance a proposal for reciprocal inspection. The US should be prepared to consider such a proposal only if the course of the UN debate indicates that this is an essential tactic in gaining support for our basic position. (A detailed scenario for handling the Cuban challenge in the UN is at Annex C.)
6. US Alternatives and Their Implications, if the Risk of a Shoot-down increases.
a. In our judgment, current arrangements provide adequate coverage to meet our surveillance requirements, there are possible political drawbacks associated with voluntary US easing of surveillance, and, as indicated above, shoot-down of a U-2 in the immediate future is unlikely. Accordingly, the US should not consider any change in current surveillance arrangements  until either (1)some clearly preferable alternative becomes available (such as through major improvements in the state of the reconnaissance art, a development that seems unlikely for the next year or two), or (2) there is significantly increased danger of a U-2 shoot-down.
b. In view of the possibility that Castro may press his threats to shoot down a U-2, by raising the issue in the UN or through other political channels, it is important to assess the feasibility and consequences of obtaining the required surveillance coverage through other means. In addition to U-2s (and on-site inspection), possible surveillance means include the following: satellites, peripheral photography, advanced aircraft, drones, balloons, SIGINT [redacted] (SIGINT, [redacted] value as supplements to other means, but cannot either individually or collectively, provide the surveillance required. They are not discussed further in this paper.) It is evident that a very large number of combinations of surveillance methods could be considered.
c. Five representative alternatives that reflect reasonably well the range of possibilities are analyzed below in term of their intelligence, military and international political implications:
(1) Combination of Techniques I (Major Reliance on Satellites).
(1) The required coverage of Cuba could be obtained by employing several techniques in a "package" program. Major reliance would be placed on satellite coverage (described below); this, together with peripheral photography, for which U-2s could be used and which would make a substantial contribution, would provide the area search required. More specific surveillance, such as follow-up of leads developed by satellites or other means, could be provided by sporadic U-2 flights could be programmed to avoid SAM sites, as described in paragraph 6c (2) below). The advanced aircraft (see paragraph 6c (3) below) might also be used but it would be advisable to do so, if at all, only on an intermittent basis as a limited supplement to U-2s. Drones and balloons would not be employed in this mix because of the increased invitation to the Cubans to try a shoot-down (of a U-2 or drone) thus leading to a crisis. 
(ii) KM-4 photography of about 75 per cent of Cuba could be obtained monthly at an additional expense of about [redacted] annually by a modification of existing KM-4 operating practices. (At no increase in cost, about 37 per cent coverage of Cuba could be obtained.) 
(iii) The KM-4 photography provides adequate ground resolution to detect and identify MRBM fixed field sites, soft MRBM sites, and soft and hard IRBM sites, provided these missiles and sites are deployed in known patterns and signatures. It is important to note, however, that an MRBM field site of the unpatterned type, such as the San Cristobal site that was discovered in 1962, probably would not be detected or identified as a missile site from KM-4 photography. By utilizing the extensive photographic base we now hold on Cuba, however, it would possible for photo interpreters, by exceedingly careful analysis of KM-4 photography, to make a comparative terrain study and detect disturbances of the terrain of a suspicious nature. Suspicious sightings would then have to be checked out by a high resolution capability (U-2 or [redacted] to determine if the disturbance is associated with field MRBM sites.
(iv) [redacted] of facilities is being studied [redacted] 9 mos lead time) that will permit [redacted] launches from Cape Kennedy that would provide interpretable photography of at least 55 per cent of Cuba from one launching per month and of at least 85 per cent count of Cuba from two launchings per month. (Other world areas, including such of China, Southeast Asia, the Congo, Indonesia and the French Pacific Ocean nuclear test facility, would also be covered.)
(v) As compared with U-2 coverage, satellite coverage would be only somewhat less timely for "search" purposes. A phenomenon observed could be on the average of 14-15 days old in U-2 photography, and would be on the average 19 days old in satellite photography. For "quick-reaction" work, however, the appeal of both types of satellite coverage suffers significantly from a lack of timeliness. There is a delay of several days (about 5-8) for capsule recovery and photo processing, and scheduling launches on short notice would be extremely difficult. Both types of coverage, however, in particular [redacted] coverage from Cape Kennedy, would be very appealing if delays could be accepted of about 15 days from launch before results are obtained. Satellite coverage is also relatively high in cost (about [redacted] per launch for Kh-4 and [redacted] respectively.)
(b) Risk. Such a package program should reduce significantly, but it would not eliminate the risk of a shoot-down of a U-2.
(c) Political Implications.
(i) The political disadvantages of such program would be minimal if the US was willing to publicize its improved technological capabilities and the corresponding reduction in the need for U-2 flights. (The publicity required might compel the US to relax existing security restrictions regarding its observation satellites and might require the disclosure of US satellite capabilities and of some satellite photography.)
(ii) On the other hand, even though the US would continue to assert the right to overfly Cuba "as required", it might be difficult to prevent unfavorable speculation concerning US motivations. There would also probably be some political (and possibly operational) disadvantages in sporadic U-2 (or advanced aircraft) flights as contrasted to more or less routinely scheduled flights. It is possible that reducing the frequency of U-2 flights would have some appeal to world opinion. But in this connection, the US would presumably always claim that only the essential minimum number of flights was being made, and would seek to avoid being committed to any specific frequency. There is therefore some question as to whether the "package" program would produce strong political advantages as a result of the impact of reducing the number of flights. Moreover, since Castro's complaints are directed at our alleged violations of Cuban sovereignty, this combination of techniques would not entirely eliminate the basis for his complaints, and it is likely that his agitation would continue.
(2) Combination of Techniques II (Major Reliance on Mulberry Pattern U-2 Flights.)
(a) As a variant to Combination I above (which would employ U-2s only sporadically), main reliance could be placed on continuing, frequent, scheduled U-2 flights, but with the flight pattern altered to take advantage of current deployment of SAMs in Cuba. SAMs are now clustered around six sites in such a way that U-2s could overfly and photograph about 80 per cent of Cuba while avoiding the SAM defense perimeters. The area covered could be increased by employing peripheral photography techniques using U-2s. Such U-2 coverage could be supplemented by available satellite coverage, and by peripheral photography from aircraft flying off the coast.
(b) Such a package program would at least initially reduce significantly the risk of a U-2 shoot-down. However, if the Cubans are determined to try a shoot-down, they could move a SAM on relatively short notice (2 to 3 days) to a location outside existing defense perimeters thereby causing the risk to rise somewhat. Relocation of a major portion of the SAMs would require a period of several weeks.
(c) A decision to fly U-2s in such a way as to avoid the SAM sites could lead the Cubans to draw certain conclusions concerning US intent. Since Cuban sovereignty would continue to be infringed, Cuban objections to the overflights would not be lessened and indeed, the obvious attempt to avoid the SAMs might encourage the Cubans to take more adventurous actions on the assumption that the US had indicated a desire to back away from or avoid a confrontation.
(3) Substitute Advanced Aircraft for U-2 Flights.
(a) Coverage. A high-performance, high-altitude aircraft such as the SR-71 could overfly Cuba at a speed near Mach 3 and at an altitude of approximately 80,000 feet. It could provide photography comparable in quality to U-2 photography.
(b) Risk. Such an aircraft could theoretically be intercepted by an SA-2 surface-to-air missile, but the actual kill probability would be reduced by an indeterminate amount by practical operational limitations on the system such as the state of training of crews or the adequacy of available communications. There would be little risk from an SA-2 for the first mission; some small increase in risk would result from each additional mission as the defensive system acquired information and experience. There would be some military disadvantage in employing the advance aircraft because its "radar signature" and other characteristics would be disclosed in the process. Further, the aircraft would create sonic booms in its path over Cuba that would publicize its presence, thereby serving to influence Castro to attempt a shoot-down in order to save face with the Cuban people. Although, as compared with the risks attaching to the U-2 flights, the probability of a shoot-down on the initial flights of the advanced aircraft would be significantly less, the risk over a longer term (after about 10-20 missions) might be sufficiently high that the aircraft should not be committed to regular use in the Cuba surveillance program at its present stage of development
(c) Political Implications. Substitution of the advanced aircraft would result in approximately the same political pressures as are associated with the U-2. However, in the light of the sonic boom problem Castro might feel the necessity for increasing political pressure to stop the obvious infringement of Cuban sovereignty.
($) UN Air and/or Ground Surveillance.
(a) Coverage. If the US receives a clear signal that the risk of a shoot-down is increasing, and if the UN debate (see paragraph 5 above) has not already occurred, the US could propose that the UN provide the personnel to operate a manned serial surveillance effort over Cuba, or a ground inspection system in Cuba, or some combination of both. For example, U-2s might be flown on behalf of the UN by Canadian pilots; or UN ground inspection teams could operate in Cuba. To be acceptable to the US, such a scheme would have to provide continuing access to the facts the US requires concerning offensive missiles in Cuba.
(b) Risk. Such an arrangement would eliminate the risk of a shoot-down of a US-manned U-2 but the US will face the possibility that, once having turned over surveillance operations to the UN, it will unable to assure itself that adequate coverage is obtained. The US might seek to retain a residual right to overfly, but it is questionable whether, practically speaking, we could ever invoke it again except in the most extreme circumstances.
(c) Political Implications. The UN reaction to such a proposal cannot be predicted with certainty. There might be objections from many nations to the principle of UN flights over sovereign territory; on the other hand, there was substantial support for UN inspection in Cuba in 1962. (For political implications of a possible US offer of reciprocal inspection, see paragraphs Sb and Sc above.)
(5) Continue Current Program.
(a) Coverage. Even if the US received indications that the risk of a shoot-down was increasing, consideration should be given to continuing the current program. Current surveillance coverage meets US requirements.
B. Risk. Continuing the current program would not reduce the risk of a U-2 shoot-down. (The risk could probably be reduced somewhat, however, by taking advantage of current SAM deployments in Cuba, as described in paragraph 6c (2) above. The risk could also be reduced by employing advanced ECM techniques. Use of ECM techniques raises possible problems of disclosure; see paragraph 7b(5) below.)
(c) Political implications. This course of action would have the political advantage of presenting firm US determination in the face of the Cuban challenge. There might be some adverse international reaction because of the continuing risk of crisis. But a shoot-down would be a major step for Castro to undertake; he must anticipate, perhaps increasingly so since the Tonkin episode, that the US would retaliate. In this connection, although it is not yet possible to determine definitely the nature of Cuba's relations with the new Soviet Government, it appears probable, on balance, that the USSR will seek to avoid deeper involvement in Cuba.
7. US Alternatives, and Their Implications, After a Shoot-down.
a. In the event that a U-2 is shot down, presently approved contingency planning calls for a prompt retaliatory strike against the SAMs; this appears to be a response appropriate to the occasion. It is possible, but seems unlikely, that the Soviets would counter-retaliate elsewhere (e.g., Turkey). It seems more probable that the Soviets would warn of consequences if the US persists with its "aggression"; and that the Cubans would seek with Soviet assistance to bring UN pressure against the US. If a shoot-down occurred and the US failed to retaliate, our position in the Cuba situation and world-wide would be severely damaged. Accordingly, our discussion of alternatives following a shoot-down begins with the premise that the retaliates in every case; the alternatives relate to subsequent actions.
b. In this context, the five representatives alternatives previously considered are analyzed below in terms of their intelligence, military and political implications. In addition, consideration is given to possible use of low-level reconnaissance, drones and balloons.
(1) Combination of Techniques I (Major Reliance on Satellites).
Coverage, risk and political implications would be essentially the same as discussed in paragraph 6c(1) above, except that it might, after a shoot-down, be relatively more advantageous to employ drones and/or balloons in the mix, (See paragraph 7b(6) below); and there would be an added possibility that the Cubans could claim they had induced the US to change it surveillance methods.
(2) Combination of Techniques II (Major Reliance on Mulberry Pattern U-2 Flights).
Coverage, right and political implications would be essentially the same as described in paragraph 6c(2) above, except for the added possibility that the Cubans could claim they had induced the US to change its surveillance methods.
(3) Substitute Advanced Aircraft for U-2 Flights.
Coverage, risk and political implications would be essentially the same as discussed in paragraph 6c(3) above.
(4) UN Air and/or Ground Surveillance.
(a) It is possible that, after a shoot-down followed by US retaliation, a UN offer to man overflights or establish ground inspection might have some appeal. Coverage and risk would be as discussed in paragraph 6c(4) above. Political implications might be somewhat different, as indicated below.
(b) Although it could be anticipated that there would be Cuban and Soviet resistance to UN surveillance proposals, they might prefer this to escalation of the conflict. They might also conclude that it would be easier ultimately to get UN surveillance discontinued then to stop US overflights. For the US, this proposal would present a dilemma. The US could not be confident that coverage under UN sponsorship would be adequate or would continue as long as needed. (The US could, of course, protect itself to some extent by the use of satellites and peripheral photography.) On the other hand, it can be anticipated that world opinion, alarmed by the US-Cuban shootings, would apply pressure for the US to accept a seemingly adequate arrangement.
(c) If the US had offered a reciprocal UN inspection arrangement before a shoot-down, such a proposal might well be revived by third parties after a shoot-down and US retaliation. There would doubtless ensue a complicated dispute over exact terms. During the period required for negotiation, the UN might make an interim demand for cessation of all provocative acts. Whether, under such circumstances, the US could continue overflights, it would be difficult to resume them in the likely event that negotiations over reciprocal inspection collapsed. In this process, the US would run the risk of a serious erosion of the justification for overflying Cuba that grew out of the 1962 crisis.
(5) Continue Current Program.
(a) Coverage. Would remain adequate
(b) Risk. It is possible that the Cubans might shoot down a second U-2 after a US retaliatory attack on their SAMs, although this would be less likely if U-2 flights were resumed after a period of low-level reconnaissance (see paragraph 7b(6)(1) below). In this connection, the US might also consider employing advanced ECM techniques to provide protection for rescued U-2 flights. This would involve some disclosure of ECM information, and the Joint Chiefs of Staff might be requested to examine the military implications of the precise circumstances under which ECM might be employed, but such employment might well be justifiable. Another variant that could be considered after a shoot-down would be sending in a drone, possibly configured to resemble a U-2, as a test of Cuban intentions before resuming U-2 flights. As a further variant, one of more advanced aircraft flights could be employed prior to reinstitution of U-2 flights.
(c) Political Implications.
In the event of a second U-2 shoot-down, the US could intensify and expand its retaliatory strikes. Continued shoot-downs would seem to offer an unprofitable exchange for the Cubans, although such an exchange would increase the pressure on the Soviets to support the Cubans. A more probable Cuban reaction would seem to be increased efforts on their part to promote UN intervention. Continuing U-2 flights would maintain the US political position in the Cuban situation.
(6) Low-level Reconnaissance, Drones and Balloons.
(a) Following a U-2 shoot-down and US retaliation, the US could initiate low-level reconnaissance flights over Cuba. This would be highly obnoxious to Castro, and might provoke an irrational response. However, the purpose of initiating such flights would be to provide a better basis for "compromising" on going back to high-level (U-2) flights. Low-level reconnaissance flights would of course be advantageous militarily in terms of the quality of intelligence that could be obtained.
(b) Drones alone could not provide the required quantity of coverage of Cuba unless a prohibitively large number of flights (at least 40-50 during the spring-summer period) were made monthly. Drone surveillance alone would eliminate the risk of losing a manned aircraft. Politically, resorting to drone operations alone would likely be taken as an indication of some softening of the US position. Although drones should not be employed prior to a U-2 shoot-down, they might be used advantageously as part of a mix after a shoot-down, or at least as a test of Cuban intentions before resuming U-2 flights.
(c) Balloons can provide substantial area coverage (about 40-70 per cent of Cuba depending upon the month) comparable to U-2 coverage in quality and at relatively low cost. Their use would involve no danger of losing a manned aircraft, but it would involve continued violation of Cuban sovereignty, which might provoke other aggressive Cuban action. In addition, unlike drones, they operate at an altitude (about 100,000 feet) at which SAMs are of little effect. While probable political reactions to balloons makes it inadvisable to employ them prior to a shoot-down, they might advantageously be included in a mix after a shoot-down.
 Scheduling of mission, to achieve a sampling effect, or duplication of coverage, is not a part of the requirement. Thus, if a particular capability could produce 90 per cent coverage in a few consecutive days in the four-week period (although this is unlikely even when U-2s are used), the requirement would be satisfied.
 This is not, however, intended to preclude some reduction in frequency of U-2 flights provided the requirement stated above can still be met. Recent long-term weather studies indicate, for example, that for more than half of the year the requirement can be satisfied by about 6-8 U-2 flights monthly rather than the 10 or so that are now flown.
 The capabilities of drones and balloons are described in paragraph 7b(a) (b) and (c) below.
 The modifications to "existing KM-4 operating practices" are minor, but essential to obtaining the coverage of Cuba described, since the present KM-4 orbital pattern covers a maximum of one-half of the island (and cannot cover more). Required changes (assuming two flights per month) would be a choice of one of the following:
1. Fly the present orbital on odd-numbered missions, covering one-half of the island and retaining the "two looks" at some priority targets that existing orbital patterns over the USSR/China area provide. Fly even-numbered missions to cover the remainder of Cuba ("fill gaps"), as well as most of the remainder of the USSR/China area, but missing coverage on this mission of some USSR/China priority targets and covering others not covered on odd-numbered missions. (Note: Even with existing orbits, only about one-half of the total member of priority targets is covered on each mission.)
2. Fly a nine-day synchronized orbit, as was flown on Mission 1014 (18-27 November). Practically the entire USSR/China area is searched on one mission with this type of orbit and Cuba is covered completely.
Collaterally with either choice, the orbit selected would be flown in such a manner that the satellite is over Cuba and at 1000 local time -- just prior to the cumulus cloud build-up -- instead of at 1200 local time, which is the case under present practices. The extent to which this modification would affect coverage of the USSR and China requires further study.