This Special National Intelligence Estimate prepared by the CIA in February 1963 in the aftermath of the Cuban Missile Crisis assesses the likely reactions if the United States resumed it’s low-level Blue Moon surveillance missions over Cuba. The last low-level mission before this report was flown on November 15, 1962.
Date: February 21, 1963
Title: SNIE 85-2-63: Reactions to US Low-Level Overflights of Cuba
Archival Source: "85: Cuba" folder, Box 9, National Security File: NIEs, Lyndon B. Johnson Library
Central Intelligence Agency
21 February 1963
Subject: SNIE 85-2-63: Reactions to us low-level overflights of Cuba
To estimate Soviet and Cuban reaction to the resumption of US low-level reconnaissance of Cuba on the basis of 3-4 missions a week for a two-week period, and to estimate reactions to a more extensive program on a continuing basis.
1. Soviet and Cuban forces both generally refrained from hostile action against the program of low-level flights last fall. No hostile action was taken against the two low-level missions of 9 February. This policy may be influenced by Soviet/Cuban estimates that their capabilities against low-level intrusions are poor, but the controlling factor probably has been their almost certain belief that armed action against a US plane would invite prompt and serious reprisals, thereby reopening a crisis in which the US would again enjoy major military advantages.
2. It does not automatically follow, however, that the Soviets and Cubans would adhere to this policy in the face of repeated low-level intrusions. They recognize that the more effective photographic coverage obtained from these missions would prevent them from concealing many activities which they might hope to hide from high-altitude reconnaissance. More important, low-level penetrations are far more conspicuous than high-altitude overflights and could not be so easily ignored. Considerable numbers of Cubans would be aware of these infractions of sovereignty, and Castro and the Soviets would be reluctant to be revealed as unwilling or unable to counter them. In addition, repeated to be revealed as unwilling or unable to counter them. In addition, repeated low-level flights would introduce a new factor into the situation because, unlike the case of high-altitude penetrations, the Soviets would no longer have a monopoly of the means of military response.
3. Soviet and Cuban reactions would depend in part upon their estimate of their capabilities to shoot down a low-level intruder. If they regarded their chances of shooting down a flight as virtually nil, then their alternatives for counteraction would be a general political outcry against the US or some form of Soviet reprisal elsewhere. However, we think it unlikely that the Soviets would be willing to take major action against US in such areas as Berlin carry too great a danger of a general crisis and military escalation.
4. In the remainder of this estimate, we assume that Soviet and Cuban forces can take hostile action against low-level penetrations, and thus regard themselves as faced with the decision of whether to do so . Further, we assume that Castro can take such action independent of Soviet cooperation. The judgments which follow, moreover, are subject to continuing review based on our appraisals of Soviet Cuban reactions to the program undertaken.
Reactions Under Various Circumstances
5. Soviet and Cuban reactions would vary in accordance with several factors. In addition to the possible influence of developments elsewhere in world affairs, the chances of a hostile response would rise with the frequency of overflights, the use of night photography, the number of Cubans exposed to overflights, the publicity given the program by the US, and probably the length of time during which the program continued.
6. In the case of three or four missions a week for a two-week period, we believe that Soviet and Cuban reaction would be minimal. They probably now expect low-level flights to verify their announced troop withdrawals and will not actively oppose such observations. During this phase the Soviets could not be certain whether the US was only verifying withdrawals of personnel and equipment or was carrying out a new program directed against other intelligence objectives. Their suspicions about the purpose of the flights might be aroused by the specific targets, but we doubt that this would influence their reaction, nor do we believe they would halt the withdrawals.
7. After the scheduled withdrawal was completed, if the flights continue at about the same frequency, we do not believe that either the Soviets or the Cubans would immediately take hostile action. They would be likely to conclude that the US was still trying to collect specific intelligence information rather than delivering a calculated political affront. Moreover, the cost to their prestige and dignity would not be too great in tolerating a program of this scope for a few weeks.
8. If this program continued without interruption, or if the frequency of missions increased, the pressures on both Cuba and the USSR for an active response would grow. Castro for his part would be inclined to interpret a prolonged period of overflights on an increased scale as a US attempt to encourage passive resistance by demonstrating US power and the regime’s impotence to the Cuban population. His fears of an invasion would be intensified, and he would probably feel himself under mounting pressure to make some effective and demonstrative response. The USSR, more concerned with the dangers of escalation and less concerned with injured Cuban pride, would probably respond to Castro’s demands for counteraction by counselling continued restraint.
9. In these circumstances, the USSR would probably try to temporize for a time, perhaps privately warning the US that it could not be responsible for Castro’s actions. If overflights continued on a fairly frequent basis, however, the Soviets would suffer some loss of prestige and face a major aggravation of their relations with the Cuban regime, all the while running the danger that they would be involuntarily committed by unilateral or even irresponsible, trigger happy Cuban action. It is entirely possible that they would seek to end overflights by cooperating with Cuban forces in an attack upon a low-level intruder, but we do not believe that they would choose this response unless they had somehow persuaded themselves that they could keep the resulting tensions within manageable limits. We continue to believe that the USSR would not accept serious risks of general war over Cuba.
10. Alternatively, the Soviets might resort to a major political and propaganda campaign, hoping to gain a UN resolution condemning US overflights. Or they might explore the possibility of concessions to US demands if they came to feel that it was essential to put a stop by some means to systematic low-level overflights; these might take the form of even more withdrawals of Soviet forces made in the hope that they could persuade the US to cease its programs. Another possibility is that they would limit themselves initially to a reopening of diplomatic conversations on Cuba, holding out the prospect of further reduction in Soviet forces if the US first halted low-level reconnaissance.
11. If Castro were faced with a program of frequent flights and a Soviet refusal to take military counteraction, he probably would at some point order Cuban forces to act against low-level penetrations. We are unable, however, to predict at what point he would attempt a unilateral response.
12. While the Soviets and Cubans would weigh their actions in the light of the risks involved, there is always the possibility of an authorized shootdown, or the accidental loss of a plane over Cuba. In these circumstances the US might be unaware of the cause of loss and could accordingly be faced with an ambiguous situation.
13. Night Photography. Detonation of the flash cartridges used in night photographic missions would considerably increase the chances that air defense units would believe that they were under attack, thus considerably increasing the chance of their spontaneous hostile response.
 i.e., an approximation of the number of missions required to cover the fixed targets recommended by COMOR in a separate paper.
 See the attached vulnerability study.