America’s nuclear monopoly ended with the arrival of the Soviet bomb in 1949, but the United States continued to enjoy nuclear primacy for another decade. During the fifties, the Soviet Union’s capacity to retaliate was sharply limited because it lacked aerial-refueling capability that would enable its bombers to reach the US homeland from Soviet territory. The Soviet Union did not have a second-strike capability at all until 1960. Even with the assembly of a large strategic striking force, a process which consumed the better part of the fifties, the USSR could not be assured of penetrating the defenses by then erected over Canadian airspace. It was only with the advent of long-range bombers and ICBMs that the Soviets finally gained a second-strike capability. These developments in Soviet nuclear capability were clearly on the horizon by 1957, but did not actually come into play until 1960.
At the conclusion of World War II, the United States and the Soviet Union respectively emerged as the strongest maritime and land powers in the world. The Soviet land army, the largest concentration of manpower, artillery, and mobile armor the world had ever seen, was the biggest concern of American military strategists. The Soviet Union’s central position in Eurasia allowed the Kremlin to bring its formidable land power to bear along its entire periphery from Finland to the Far East. US’ atomic monopoly and absolute supremacy over the oceans assured the security of the US homeland. The key question facing US strategists was one of extended deterrence: how to deter a Soviet attack on the Eurasian periphery, especially Western Europe. A secondary concern was how to thwart Soviet penetration of Europe, Asia, and the Middle East. Unlike Britain in the nineteenth century, the United States was no pygmy on land. However, what was plain as day was that the US’ conventional forces-in-being were insufficient to deter a Soviet land invasion.
The solution that was hit upon was the doctrine of massive retaliation: the United States would respond to an invasion of Western Europe with an all-out nuclear attack on the Soviet Union. The threat of massive retaliation was credible enough during the brief period of atomic monopoly. Once the USSR acquired nuclear weapons, the US calculus changed irrevocably. In the event of a conventional attack on Western Europe, the first objective of US war strategy had to be the destruction of the Soviet Union’s capacity for nuclear retaliation. A counterforce strike was necessary before an all-out attack could be ordered otherwise US cities would be in grave danger. But once the adversary had been disarmed by a successful counterforce strike, an all-out attack became unnecessary to secure political obedience. This war strategy was only an effective deterrent as long as the United States enjoyed nuclear primacy. For as soon as the Soviets acquired a second-strike capability, the threat of both an all-out attack and a counter-force strike (which would immediately prompt a global thermonuclear war) lost its credibility. To put it bluntly, no US President would entertain the idea of sacrificing fifty American cities to protect West Germany.
With the end of US nuclear primacy in sight, US strategists began exploring opportunities that had opened up with technical developments in the field of nuclear weapons. The first important break-through was the hydrogen bomb. Instead of the simple fission bombs dropped over Hiroshima and Nagasaki, thermonuclear weapons were multistage devices, where a small fission reaction is used to set-off a much bigger fusion reaction (which could then set off a much larger fission chain reaction and so on). Thermonuclear devices harnessed the physics behind the source of the sun’s power to yield an explosive force that was a thousand more powerful than those known to the skies over Japan. It was quickly realized that the explosive capacity of thermonuclear devices was unbounded. Thermonuclear weapons of arbitrarily large yields could easily be built, even though a 10 megaton device was enough to effectively take out any major world city. Thermonuclear weapons enhanced the second-strike capability of nuclear powers by increasing the survivability of the deterrent: only a few of these awesome weapons need survive a surprise first-strike to serve as an effective deterrent. The Cold War adversaries would eventually go on to stockpile tens of thousands of megaton thermonuclear warheads. That was surely overkill. Strategic nuclear weapons are absolute weapons. As long as a state can absorb a surprise first-strike and still respond with a devastating counter-blow, that state has a second-strike capability that is the sole guarantee of its survival in a nuclear world. For a robust second-strike capability, the US and USSR never needed anymore than a few hundred thermonuclear devices judiciously distributed between the nuclear triad: ICBMs with thermonuclear warheads launched from land based silos in the interior, those launched from nuclear submarines constantly trying to evade detection by the adversary, and in constantly airborne long-range bombers.
The second and more important breakthrough was the discovery that yields could be lowered as desired, thereby allowing for the development of sub-strategic nuclear devices. A field army commander faced with a superior massed concentration of land power could neutralize the adversary’s conventional advantage by using low-yield devices in the theater of operations. In 1957, Kissinger argued in his book Nuclear Weapons and US Foreign Policy, that merely incorporating tactical nuclear weapons into existing World War II-era military doctrine is dangerous and myopic. For tactical nuclear weapons demand an entirely new military doctrine for fighting limited nuclear wars. Basically, conventional warfighting requires concentrations of superior firepower, mobile armor, and flying artillery. Conventional deterrence requires an ability to thwart a blitzkrieg and fight a long drawn-out war of attrition. This requires that forces-in-being have to sufficient to hold the front while superior industrial potential is mobilized to exhaust the enemy in a war of attrition. Force concentration, so essential to conventional deterrence and warfighting, is a losing strategy against an adversary willing to deploy theater nuclear weapons. To fight and win a limited war in the nuclear era requires a dispersed force structure. Units must be small, mobile, and widely dispersed to avoid detection and targeting. And they must have the capability of striking at massed concentrations of forces of the adversary, thereby denying him control of the territory.
Sir Anthony W. Buzzard had argued two years before Kissinger that the US is already following a policy of “graduated deterrence,” and doing so out of necessity. The argument is straightforward: it is simply not credible that you will respond to a sub-strategic attack with global thermonuclear war. If your only choice in response to a limited attack is launching an all-out war or folding, you will have to fold. Intermediate military options between all-out war and appeasement are necessary in a world where all-out war means suicide. The goal of limited nuclear escalation is to put the ball in the enemy’s court, and have him face the psychological pressure of pulling the trigger on global thermonuclear war. The second breakthrough solved the thorniest problem of America’s global strategy. Extended deterrence was secured by neutralizing the Soviets’ conventional superiority. Specifically, a Soviet land invasion of Western Europe was deterred by America’s threat to mount a local defense with low-yield nuclear weapons. (Japan’s defense was already guaranteed by America’s naval primacy in Asian waters.)
Even before intellectuals had begun advocating limited nuclear war, the military was busy preparing to fight one. Nato had already formally decided to field tactical nuclear weapons in Europe on December 17, 1954. The Nato war-game, “Carte Blanche,” of June 23-28, 1955, simulated a Europe-wide war with the Warsaw Pact involving field weapons. The southern half of the continent played the Warsaw Pact (“Southland”) that invades the northern half, playing Western Europe (“Northland”). The outcome was the repulsion of the attacker after a 48-hour nuclear exchange of some 355 low-yield bombs almost evenly distributed between the two adversaries. The war-game was leaked to the press and caused quite a stir in Europe, if not in the United States. Germans were horrified. For good reason: Germany would most likely be the zone of fire is a land war between Nato and the Warsaw Pact. Another Nato exercise in 1957, “Lion Noire,” confirmed that Germany would be devastated through the effects of blast and fallout. To be sure, the estimated casualties were a tiny fraction of what would obtain in a global thermonuclear war.
Meanwhile, a US army exercise in 1957, “Sagebrush,” concluded that theater nuclear weapons did not favor the defense. This meant that after losing its nuclear primacy, the United States could deter a Soviet attack on Western Europe only as long as it held a decisive advantage in fighting a limited nuclear war. “The proper analogy to limited nuclear war is not traditional land warfare,” Kissinger argued, “but naval strategy, in which self-contained units with great firepower gain the upper hand by destroying their enemy counterparts without physically occupying territory or establishing a front-line.” Prevailing in a limited nuclear war requires great mobility and stealth coupled with superior information, surveillance, and reconnaissance (ISR) capabilities. The protection of Western Europe therefore required America to maintain its substantial technological lead over the Soviet Union. In 1957, the Soviet Union’s GDP was $779 billion, for the US’ $1,859 billion and Western Europe’s $1,857 billion (all in 1990 dollars). With the Western Alliance’s nearly 5-1 advantage in economic size over the USSR, the capital intensity of the capabilities required for limited nuclear war rigged the game sharply in America’s favor.
Officially, the US never proclaimed that it would fight a limited nuclear war. The doctrine of “massive retaliation” was replaced by Kennedy’s “flexible response,” according to which tactical weapons may be deployed as a “warning shot.” This was obviously rubbish. Why would the use of a tactical device by the US in the middle of a conventional fire-fight with the Soviet Union signal an American resolve to commit suicide? There were only two ways for such a threat to succeed. Either the US could make a threat “that leaves something to chance” á la Shelling—that is, roll the die on all-out war—or the US could threaten to escalate the conflict to a limited nuclear war. The former is unpersuasive because of the following lemma in game theory: no equilibrium mixed strategy can assign a non-zero probability to a dominated pure strategy. The latter, limited escalation, is precisely what the United States intended. Tactical nuclear devices remained fielded in Europe throughout the Cold War. Soviet war planners understood that they would be used if the need arose.
The United States did not give up on conventional deterrence. The US military strategy was to fight with conventional weapons where sufficient, and escalate to the nuclear level when necessary. Once the all-or-nothing doctrine was debunked, it was realized that there were many rungs on the escalation ladder. The US sought and gained escalation dominance—the ability to establish, through favorable exchange ratios, a position so superior that the adversary is forced to yield. It developed the nuclear triad and constantly modernized its arsenal to ensure the survival of its deterrent against a a surprise first-strike. It invested heavily in ISR, precision guided munitions (PGMs), and missile defense to regain a first-strike capability. With the decay of Russia’s arsenal and warning systems, and the vanishing ability of its nuclear submarines to evade detection, the US has regained its nuclear primacy due largely to its nearly real-time global strike capability—the ability to take out any target anywhere on the planet within one hour. The US also developed a broad range of platforms for deploying tactical nuclear weapons. Ground attack aircrafts, long-range cruise missiles, littoral combat ships, and field artillery were all reconfigured to make them nuclear capable. Whether or not nuclear weapons will be used if the US comes to blows with a nuclear-armed adversary is simply a matter of whether the US will be able to thwart the challenger by conventional means alone or not.
A revisionist power preparing to overthrow the status quo in a region vital to the United States must be ready to fight a limited nuclear war. The state will have to gain the full spectrum of modern military capabilities: ISR, PGMs, high-speed propulsion and stealth technologies, remote strike over intermediate and long ranges, missile defense, and a broad arsenal of conventional and nuclear weapons of variable yield. And it will require a military doctrine that utilizes the opportunities opened up by modern weapons systems. For the attacker to rely on a conventional war strategy and hope that its strategic arsenal would deter the tactical use of nuclear weapons would be playing into the defender’s hands. A conventional war strategy with its massed forces is an invitation for the deployment of tactical nuclear weapons to foil the advance. Therefore, the attacker must plan on fighting a limited nuclear war from the get-go. In light of these findings, we need to reconsider the asymmetric escalation game with the limited war scenario (outcome DD) now interpreted as a limited nuclear war. The results of that investigation still hold mutatis mutandis. The bottomline is that extended deterrence will continue to hold in Asia until China has a viable strategy for prevailing in a limited nuclear war.