Johnny Ryan's A History of the Internet and the Digital Future has just been released and is already drawing rave reviews. Ars Technica is proud to present three chapters from the book, condensed and adapted for our readers. This first installment is adapted from Chapter 1, "A Concept Born in the Shadow of the Nuke," and it looks at the role that the prospect of nuclear war played in the technical and policy decisions that gave rise to the Internet.

A Concept Born in the Shadow of the Nuke

The 1950s were a time of high tension. The US and Soviet Union prepared themselves for a nuclear war in which casualties would be counted not in millions but in the hundreds of millions. As the decade began, President Truman's strategic advisors recommended that the US embark on a massive rearmament to face off the Communist threat. The logic was simple:

A more rapid build-up of political, economic, and military strength... is the only course... The frustration of the Kremlin design requires the free world to develop a successfully functioning political and economic system and a vigorous political offensive against the Soviet Union. These, in turn, require an adequate military shield under which they can develop.

The report, NSC-68, also proposed that the US consider pre-emptive nuclear strikes on Soviet targets should a Soviet attack appear imminent. The commander of US Strategic Air Command, Curtis LeMay, was apparently an eager supporter of a US first strike. Eisenhower's election in 1952 did little to take the heat out of Cold War rhetoric. He threatened the USSR with "massive retaliation" against any attack, irrespective of whether conventional or nuclear forces had been deployed against the US. From 1961, Robert McNamara, Secretary of Defense under Presidents Kennedy and Johnson, adopted a strategy of "flexible response" that dropped the massive retaliation rhetoric and made a point of avoiding the targeting of Soviet cities. Even so, technological change kept tensions high. By the mid 1960s, the Air Force had upgraded its nuclear missiles to use solid-state propellants that reduced their launch time from eight hours to a matter of minutes. The new Minuteman and Polaris missiles were at hair-trigger alert. A nuclear conflagration could begin, literally, in the blink of an eye.

Yet while US missiles were becoming easier to let loose on the enemy, the command and control systems that coordinated them remained every bit as vulnerable as they had ever been. A secret document drafted for President Kennedy in 1963 highlighted the importance of command and control. The report detailed a series of possible nuclear exchange scenarios in which the President would be faced with "decision points" over the course of approximately 26 hours. One scenario described a "nation killing" first strike by the Soviet Union that would kill between 30 and 150 million people and destroy 30-70 per cent of US industrial capacity. Though this might sound like an outright defeat, the scenario described in the secret document envisaged that the President would still be required to issue commands to remaining US nuclear forces at three pivotal decision points over the next day.

The first of these decisions, assuming the President survived the first strike, would be made at zero hour (0 H). 0 H marked the time of the first detonation of a Soviet missile on a US target. Kennedy would have to determine the extent of his retaliatory second strike against the Soviets. If he chose to strike military and industrial targets within the Soviet Union, respecting the "no cities doctrine," US missiles would begin to hit their targets some thirty minutes after his launch order and strategic bombers already on alert would arrive at H + 3 hour. Remaining aircraft would arrive at between H + 7 and H + 17 hours.

Next, the scenario indicated that the President would be sent an offer of ceasefire from Moscow at some time between 0 H and H + 30 minutes. He would have to determine whether to negotiate, maintain his strike or escalate. In the hypothetical scenario, the President reacted by expanding US retaliation to include Soviet population centres in addition to the military and industrial targets already under attack by the US second strike. In response, between H + 1 and H + 18 hours, the surviving Soviet leadership opted to launch nuclear strikes on western European capitals and then seek a ceasefire. At this point, European nuclear forces launched nuclear strikes against Soviet targets. At H + 24 the President decided to accept the Soviet ceasefire, subject to a withdrawal of the Soviet land forces that had advanced into western Europe during the 24 hours since the initial Soviet strike. The President also told his Soviet counterpart that any submerged Soviet nuclear missile submarines would remain subject to attack. The scenario concludes at some point between H + 24 and H + 26 when the Soviets accept, though the US remain poised to launch against Soviet submarines.

A nuclear detonation in the ionosphere would cripple FM radio communications for hours, and a limited number of nuclear strikes on the ground could knock out AT&T's highly centralized national telephone network.

In order for the President to make even one of these decisions, a nuclear-proof method of communicating to his nuclear strike forces was a prerequisite. Unfortunately, this did not exist. A separate briefing for Kennedy described the level of damage that the US and USSR would be likely to sustain in the first wave of a nuclear exchange. At the end of each of the scenarios tested both sides would still retain "substantial residual strategic forces" that could retaliate or recommence the assault. This applied irrespective of whether it had been the US or the Soviet Union that had initiated the nuclear exchange. Thus, despite suffering successive waves of Soviet strikes, the United States would have to retain the ability to credibly threaten and use its surviving nuclear arsenal. However, the briefs advised the President, "the ability to use these residual forces effectively depends on survivable command and control..." In short, the Cold War belligerent with the most resilient command and control would have the edge. This had been a concern since the dawn of the nuclear era. In 1950 Truman had been warned of the need to "defend and maintain the lines of communication and base areas" required to fight a nuclear war. Yet, for the next ten years no one had the faintest idea of how to guarantee command and control communications once the nukes started to fall.

A nuclear detonation in the ionosphere would cripple FM radio communications for hours, and a limited number of nuclear strikes on the ground could knock out AT&T's highly centralized national telephone network. This put the concept of mutually assured destruction (MAD) into question. A key tenet of MAD was that the fear of retaliation would prevent either Cold War party from launching a first strike. This logic failed if a retaliatory strike was impossible because one's communications infrastructure was disrupted by the enemy's first strike.

RAND, a think tank in the United States, was mulling over the problem. A RAND researcher named Paul Baran had become increasingly concerned about the prospect of a nuclear conflagration as a result of his prior experience in radar information processing at Hughes. In his mind improving the communications network across the United States was the key to averting war. The hair-trigger alert introduced by the new solid fuel missiles of the early 1960s meant that decision makers had almost no time to reflect at critical moments of crisis. Baran feared that "a single accidental[ly] fired weapon could set off an unstoppable nuclear war." In his view, command and control was so vulnerable to collateral damage that "each missile base commander would face the dilemma of either doing nothing in the event of a physical attack or taking action that could lead to an all out irrevocable war." In short, the military needed a way to stay in contact with its nuclear strike force, even though it would be dispersed across the country as a tactical precaution against enemy attack. The answer that RAND delivered was revolutionary in several respects—not least because it established the guiding principles of the Internet.