Michael Dobbs - One Minute to Midnight

The gloom was particularly intense in the forward part of the ship, home to R Branch, which specialized in high-frequency microwave transmissions and Morse code signals. The Cuban microwave network had been installed by an American company, Radio Corporation of America, during the Batista period. Armed with a complete map of the network and technical details of the transmissions facilities, the eavesdroppers on board the Oxford were able to record and analyze some tantalizing communications traffic. Among the circuits they succeeded in breaking at least partially were the Cuban secret police, the Cuban navy, the police, air defenses, and civil aviation. For the trick to work, the ship had to be stationed between microwave transmission towers in the Havana area. The quality of the intercept fell sharply whenever the Oxford pulled back more than a dozen miles from the Cuban coast.

Prior to October 22, the Oxford had been making lazy figures-of-eight along the coast, usually well within sight of El Morro Castle, Havana’s most visible landmark from the sea. Traveling at around 5 knots, the vessel would steam eastward for sixty or seventy miles, then head back in the opposite direction, repeating the pattern over and over. The Oxford was officially described as a “a technical research ship,” conducting studies on “radio wave propagation,” in addition to gathering “oceanographic data.” The Cubans were not deceived. They saw the towering antennae on the stern and aft decks and concluded that the Oxford was “a spy ship,” whose primary purpose was to scoop up their communications. The Cuban military sent out messages warning of the dangers of “loose talk” over the phone.

The Cuban navy played a continuous cat-and-mouse game with the Oxford. On one occasion, it sent patrol boats to photograph the spy ship. On another, a Cuban gunboat approached within a few hundred yards. The Elint operators could hear the fire-control radar on the gunboat emitting a series of beeps in search of a target. When the radar locked on to the target—the Oxford herself—the beeps became a steady tone. Up on deck, the crew saw Cuban sailors aiming heavy guns in their direction. After staging its mock attack, the gunboat veered away.

Stripped of its World War II fittings, the Oxford functioned as a giant electronic ear. The signals captured by the communications masts were broken down and piped belowdecks, where they were analyzed by teams of electronics engineers and linguists. Each specialty had its own traditions and lingo. The Morse code experts, for example, were known as “diddy chasers” because they spent their working hours transcribing dots and dashes. It was the “diddy chasers” who demonstrated that the Soviets were assuming control of Cuban air defenses. On October 9, they picked up evidence that the grid tracking system used by the Cubans to locate aircraft was practically a carbon copy of a system previously used by the Soviets.

Even after the Oxford pulled back, it was still able to pick up Soviet radar signals from the Havana area. Analyzing the signals was the responsibility of T Branch—a small, eighteen-man department that occupied the aft part of the ship. Four men were usually on duty in the Receiver Room, scanning known radar frequencies and switching on their recorders whenever they heard anything interesting. The most valuable information came from the surface-to-air missile sites that formed a defensive ring around Cuba. Used to shoot down Gary Powers, the V-75 SAM missile was the weapon most feared by American pilots. It operated in conjunction with two radar systems: a tracking, or target acquisition, radar known to NATO as “Spoon Rest” and a fire control radar known as “Fruit Set.” The Spoon Rest radar would be activated first. The Fruit Set radar would only be switched on if a target was in sight or the system was being tested.

The Oxford had first detected a Spoon Rest radar in Cuba on September 15. It was evidently just a test because the radar, west of Mariel, was soon switched off. On October 20, T-branchers picked up signals from a Fruit Set radar. This suggested that the SAM missiles were fully checked out and could be launched at any time. The development was so important that the head of the Navy’s cryptological agency insisted on seeing the evidence himself. That night, the Oxford put into Key West for thirty minutes so that Admiral Thomas Kurtz could retrieve the tapes.

The next big breakthrough came shortly after midnight on Black Saturday. The Oxford had just begun her slow loop eastward. The spy ship was now seventy miles off the coast of Cuba, too far to pick up the microwave signals, but close enough to detect radar signals. At 12:38 a.m., T-branchers picked up the whoop of an air defense radar from a SAM site, just outside Mariel. They turned on their recorders and got out their stopwatches, measuring the interval between the buzzing sounds and consulting a bulky manual that contained the identifying characteristics of all known Soviet radar systems, including frequency, pulse width, and pulse repetition rate. The manual confirmed what they already suspected. It was a Spoon Rest radar.

This time, the Soviets did not turn the radar off, as they had done previously when they were only testing the system. Soon, the Oxford was picking up Spoon Rest signals from SAM sites at Havana East (the site visited by Castro on October 24) and Matanzas, in addition to Mariel. The radar systems at all three sites were still active nearly two hours later when the National Security Agency sent out its first flash report. Since the spy ship was moving slowly down the coast, the T-branchers were able to take multiple bearings on the source of the radar signals and establish the precise locations of the SAM sites.

The activation of the radar systems coincided with the discovery of a major change in the organization of Cuban air defenses. NSA analysts noticed that Cuban call signs, codes, and procedures were replaced by Soviet ones in the early hours of Saturday morning. Commands were issued in Russian rather than Spanish. It looked as if the Soviets had taken over and activated the entire air defense network. Only the low-level antiaircraft guns remained under Cuban control.

There was only one possible conclusion: the rules of engagement had suddenly changed. From now on, American planes flying over Cuba would be tracked and targeted.

Nine time zones to the east, it was already midmorning on the Soviet missile testing range at Baikonur, in the arid plains of southern Kazakhstan. Boris Chertok was late getting up. The rocket designer had been working for weeks preparing the Soviet Union’s latest space spectacular, a probe to Mars. He had been awake most of the night, worrying about the project. One launch had already failed after a rocket engine misfired. A second attempt was planned for October 29.

When he got to the rocket assembly hall, he could scarcely believe his eyes. Heavily armed soldiers had taken over the building, and were carefully checking the identities of anyone entering and leaving. Nobody was paying any attention to the Mars rocket. Instead, engineers were swarming around an unwieldy five-engined monster previously covered with tarps. Nicknamed the Semyorka—“ the little seven”—the R-7 had won worldwide fame as the rocket that launched Sputnik and Yuri Gagarin into orbit. But it was fast becoming obsolete. All that it was good for now was to deliver a 2.8-megaton nuclear warhead to wipe out New York, Chicago, or Washington. The Soviets had so few intercontinental ballistic missiles in service that they had to make use of every single rocket in the inventory, outdated or not.