On October 18, 1962, the Central Intelligence Agency released a "Joint Evaluation of the Soviet Mission Threat in Cuba," based on intelligence obtained as of 9 p.m. that day. The evaluation, prepared by the Guided Missile and Astronautics Committee, the Joint Atomic Energy Intelligence Committee, and the National Photographic Interpretation Center, was codenamed Iron Bark because it drew upon intelligence material provided by the Central Intelligence Agency's important Soviet source, Colonel Oleg Penkovsky. It was based on "relatively complete photo interpretation of U-2 photography" made on missions of October 14, and two on October 15 and "very preliminary and incomplete readout" of coverage of six U-2 missions on October 17.
The evaluation concluded that there was "at least one Soviet regiment consisting of eight launchers and sixteen 1020-nm (SS-4) medium-range ballistic missiles now deployed in western Cuba at two launch sites." These mobile missiles had to be considered operational and could be launched within 18 hours after the decision to launch was made. The evaluation concluded that "Fixed, soft sites, which could achieve initial operational capacity during December 1962, are now being deployed near Havana." These sites were probably intended for 2200-nm (SS-5) intermediate-range ballistic missiles and could be operational by December 1962. All missiles were manned by Soviet personnel and were under Soviet control. Although there was no positive evidence of nuclear warheads in Cuba, the evaluation suggested that "one must assume that nuclear warheads could now be available in Cuba to support the offensive missile capacity as it becomes operational." The expected warheads for these missiles would weigh 3,000 pounds and have yield in the low megaton range.
The significance of these developments, according to the evaluation, was that the Soviet Union "intends to develop Cuba into a prime strategic base, rather than as a token show of force. The mixed force of 1020-and 2200-nm missiles posed a common threat to the United States and a large portion of Latin America. (Central Intelligence Agency, Job 80-R01386R, O/D/NFAC, Cuba, 5 Sept-19 Oct 1962) See the Supplement. An extract of this evaluation is reproduced in CIA Documents on the Cuban Missile Crisis, 1962, pages 187-191.