‘This is the result of the photography taken Sunday, sir. There’s a medium-range ballistic missile launch site and two new military encampments … in West Central Cuba. The launch site at one of the encampments contains a total of at least 14 canvas-covered missile trailers, measuring 67 feet long and more than nine feet in width.”

On a Tuesday morning in October 1962, these chilling words informed President Kennedy and his advisors that the Soviet Union was constructing nuclear missile sites in Cuba. Thanks to recording devices established and activated by JFK, we can actually hear CIA briefer Marshall Carter and deliver this precise analysis of U.S. spy plane photos. Their tone appears calm and measured, yet this briefing would light the touch paper for the Cold War’s most dramatic crisis. Nuclear missiles now lay in place merely 90 miles off the U.S. coast, contrary to the express assurances of Soviet Premier Khrushchev and in the face of repeated warnings from President Kennedy in preceding months.

These missiles presented a dramatic challenge to the precarious balance of Cold War power, and the next 13 days would see a dangerous stand-off between two nuclear superpowers with a combined arsenal of some 4,000 warheads. Before the crisis was resolved, one of these warheads would be ordered for launch.

Robert F. Kennedy, JFK’s younger brother, was 36 years old at the time. One of the youngest attorneys general ever appointed, RFK was also the president’s de facto chief of staff and most trusted advisor. Known as “that terrier of a man” by some in the Kennedy administration, RFK was profoundly committed to his brother’s success. On the campaign trail for his brother years earlier he had remarked, “I don’t care if anyone likes me, so long as they like Jack.” He carried this temperament through to the president’s administration, doggedly pursuing his brother’s objectives, ever ready to cut through departmental etiquette to ask forceful questions and to challenge the answers.

By October 1962, he had already proved himself indispensable to the president. It was to his younger brother that the president had turned after a botched invasion of Cuba in 1961 (the Bay of Pigs fiasco), appointing him head of a task force examining the causes of the disaster. A year later, it was no surprise that RFK was one of the first to be notified of the missiles, receiving an urgent phone call from the president a few hours ahead of the CIA briefing.

In the coming days and weeks RFK would make a unique and indispensable set of contributions to resolving the crisis. We are now able to follow these contributions in rich detail, thanks to the remarkable in-the-room access provided by the White House tape recordings, as well as new archival sources recently declassified.

First, RFK went after the raw data. His personal files on the crisis hold as many as 3,584 documents directly reviewed by him over the period. Immediately after hanging up the phone to his brother, he coordinated a private briefing with the CIA. Joining cabinet discussions later that morning, RFK was already extremely well-briefed on the missile sites, their disposition and readiness.

Such preparation was an RFK trademark, especially where it required out-of-the-box thinking. In his private notes on the Bay of Pigs disaster, RFK had judged “underestimation” of Castro’s forces as a key failing of the Kennedy administration. Determined not to repeat the mistake, RFK was one of only two presidential advisors to predict the installation of missile sites in Cuba, warning his brother of the possibility over a year before the crisis.

He then took active measures to prepare for the possibility, instructing the Departments of State and Defense to investigate possible responses, whilst also outlining his own proposals in interdepartmental security briefings. These proposals were remarkably prescient of those actually debated and subsequently chosen during the Cuban Missile Crisis. As a direct result of RFK’s proactive, terrier-like energy, the key government departments tasked with handling the Cuban missile crisis had been remarkably well-prepared in contingency thinking and intelligence.

Perhaps even more importantly, so had the president’s closest advisor. As the crisis developed, RFK continued to seek new information and advice, acting as his brother’s eyes and ears—able to go where he could not, to source frank perspectives unhindered by presidential deference. At times this meant spotlighting another advisor’s counsel in a cabinet meeting; at others summarizing a loud mess of opinions into a coherent range of actionable options for the president.

In a few unique circumstances, it even meant playing up a blunter edge to his persona, asking the sort of direct questions the president could not. In one remarkable exchange during the crisis, apparent in the tapes, the president can actually be heard whispering instructions to RFK on a difficult question he wanted put to the head of the CIA. RFK also held a number of pivotal one-on-one conversations with fellow advisors during the crisis, privately relaying these back to the president in a number of off-the-record discussions.