Among the most effective strategies for dealing with uncertainty and surprise is diversification. The United States has historically sought variety in all its approaches to defense, deterrence, and disarmament in its efforts to shore up strategic stability. A look at nuclear delivery platforms and associated technology provides a classic example of this thinking.
Recalling the “air, earth, water, and fire” of antiq-uity, most discussion of technology and strategic sta-bility involves the classical “Triad” of aircraft, ICBMs, submarine-launched ballistic missiles (SLBMs) and the weapons they carry. Often missed is the diver-sity within each category and the synergism among them. Also, weapons and delivery systems are part of a broader system shaped by technology supporting nuclear, conventional, and unconventional capabili-ties. This broader system, in turn, nests into a system of policies, process, and organizations that exploit technology and are influenced by it.
The manned bomber was the first nuclear delivery system and has been retained for the nuclear mission with and without standoff missiles for many reasons.
Because they are already assigned conventional mis-sions, manned bombers, including tactical aircraft, are readily available, dual-use assets. Placing bombers on alert and dispersing or deploying them in highly vis-ible ways makes them the favored force for strategic signaling, and dual-use aircraft are important elements
as stealth, standoff missiles, and electronic counter-measures increase the cost of air defense against them.
Their slow flight times, “man-in-the-loop,” and ability to be recalled are stabilizing characteristics even when they are involved in nuclear signaling. If deployed in combat for conventional or nuclear strikes, surviving bombers can in theory be reconstituted as a deterrent in efforts to re-establish stability. In general, bombers have been favored in arms control agreements over fast flying ballistic missiles. They were excluded from SALT I, favored under discounting rules in START I, and more heavily discounted in New START.
Bombers present some concerns as well. Main-taining high readiness and alert levels, highly trained personnel, and tankers for air-to-air refueling can be very expensive. Aircraft not on alert are vulnerable to surprise attack, and any on alert would still face de-manding time requirements to escape ballistic missile attack, especially from depressed trajectory attacks from SLBMs. Uncertain bomber performance against improved air defenses can lead to uncertainty about survivability and the inability to reach all targets.
Long flight times and uncertain penetration could complicate some escalation control and damage limi-tation missions, especially if other nuclear systems get diverted to thin out air defenses. Bomber bases are few, and the number of bombers is small. Deploy-ments overseas can be difficult and controversial. As symbols of coercion or defiance, both nuclear and con-ventional bombers and their bases are also potentially prime targets.
The land-based missile, ultimately of interconti-nental range, revolutionized nuclear deterrence. With relatively low operating costs, very high readiness rates, timely response, considerable targeting
flexibil-ity, and high confidence in reaching and destroying point targets, ICBMs became the centerpiece of force exchange analysis and the psychology and dynamics of deterrence. For the Soviet Union in the Cold War, they were the measure of merit among nuclear-armed missiles. Deployment of single-warhead ICBMs is widely seen as stabilizing because any attack on them would likely require more warheads than those de-stroyed, possibly many more. Attacking single war-head missiles deployed in hardened silos or on mobile launchers would require a major escalation of warfare across the sovereign heartland of a nuclear-armed nation. As a total force, they do not offer an attacker the prospect of a simple fait accompli. With secure and reliable communications to command centers capable of obtaining the most up to date information, launch orders could occur shortly before the required “time on target.” This could give decisionmakers more time to consider options, including escalation restraint or damage limitation. Accurate attribution of who had attacked and from where is also a stabilizing feature of ICBMs.
ICBMs, too, present challenges. Some operational ICBM trajectories might overfly populated areas or might be misinterpreted by a country not under attack.
More significantly, highly MIRVed ICBMs became the symbol of instability arithmetic because every missile with multiple warheads attacking multiple missiles with multiple warheads greatly leveraged the value of striking first. This also magnified their coercive symbolism. The low cost of such systems per warhead made such MIRVed systems attractive when deployed nuclear arsenals were very large, even if they consti-tuted only a small percentage of the total force.
Nev-the force exchange ratio calculations that still inhabit nuclear stability analysis. The subsequent search for more survivable basing modes also drove up costs and generated NIMBY backlashes against new de-ployments, particularly in democratic nations.
The SLBM carried on nuclear submarines over-came a number of concerns associated with ICBMs and bombers. Submarines were not on sovereign soil if attacked. They could be relocated so as not to overfly nonhostile countries. Nuclear submarines with ballis-tic missiles (SSBNs) could remain underwater on long voyages through large patrol areas, providing a high degree of survivability to the large number of nuclear warheads deployed on each submarine at sea. Modern SLBMs can be highly accurate. Although some SLBMs have intercontinental range, SLBMs could use de-pressed trajectories from launch points closer to their targets to reduce flight time. SLBM flight paths can be more variable, thus complicating defenses against them. America’s nuclear allies have SLBMs, giving them somewhat more political acceptability.
The SSBN force also presents challenges. SSBNs are expensive to acquire and operate. As the number of warheads on each submarine is reduced, “sticker shock” in the form of cost per warhead on station goes up radically. The alternative, continued concentration of large numbers of warheads on just a few subma-rines means that at low force levels only a small per-centage of the total warheads will actually be at sea.
At very low numbers, attacks, accidents or human in-cidents could reduce or eliminate a sea-based compo-nent unexpectedly. Depending on the size of the sub-marine force and its deployment status, maintenance requirements can mean that many, most, or nearly all warheads on submarines will be vulnerable in port.
Submarine bases thus can be highly attractive iconic targets in attempts at “fait accompli” strikes, catalytic interventions by third parties, and conceivably sym-bolic attacks by terrorists.
At sea, SSBNs benefit from Navy-wide counter-antisubmarine warfare (ASW) advances. The oceans are huge. Still, advanced ASW capabilities are in great demand.27 SSBNs could become vulnerable even dur-ing the conventional phase of a conflict. In any phase of conflict, a submarine launching any limited attack runs the risk of disclosing its position. All nuclear delivery platforms run the risk of loss of communi-cations under attack, but securing extensive, reliable communications with a submarine underwater dur-ing hostilities can present additional challenges. Al-though missile submarines can add targeting flexibil-ity, they are sometimes equated in public debate with all out nuclear use or pre-emptive and decapitating strikes. Generally, submarines have avoided NIMBY problems except around bases, although accidents at sea and the disposal of reactor cores have been is-sues for several countries. Those nuclear-weapons states that deploy SLBMs have made clear that they currently will not accept any nuclear-free zones that would ban nuclear weapons or nuclear reactors at sea or constrain transit. Entry of nuclear-powered ships is denied to some ports, but SSBNs do not normally have that requirement. Still, movement to global nuclear zero may increase pressure to ban nuclear weapons and even nuclear propulsion in international waters.
The diversity of the nuclear “Triad,” or “Tetrad”
if one counts dual-use fighter-bombers, is often de-scribed as a hedge with one or more backups for the failure of any one leg. That is only part of the story.
U.S. strategy has sought to exploit diversity to get greater synergism and flexibility at lower cost. Each component has its special strengths, but also its weak-nesses. Diversity aims at having the total contribution be greater than the sum of the parts, but diversity is not always the lowest cost.
Many decisions about the employment of technol-ogy, including military technoltechnol-ogy, involve trades be-tween the virtues and vices of simplicity with those of diversity. Simplification typically offers reductions in Research and Development (R&D) and support base costs, brings economy of scale to production and op-erations, and permits a narrower business focus. Di-versity typically offers more flexibility and resiliency, but with that comes further complexity. Each has its advantages. Each tends toward a different form of optimization. Simplification often optimizes toward unit economic cost or inputs. Diversity tends to look at unit mission cost, largely an output. Simplification seeks harmony with expectations and trends. Diver-sity tends to hedge against uncertainty.
Diversity is a common strategy for dealing with uncertainty, surprise, and complexity, whether we are dealing with finance, sports, technology start-ups, or strategic stability. Investors are discouraged from concentrating their assets. Athletic teams pick players with different size, speed, and skills, hoping to find the winning mix at the right price. High tech entrepre-neurs seek to leverage the undervalued.
Diversity makes available a number of tactics, for example:
• Complementation, the ability to assist or enable others;
• Supplementation, an ability to make up for de-ficiencies of others;
• Substitution, an ability to switch one for anoth-er to compensate for losses;
• Synergism, the ability for the total to be greater than the sum of the parts;
• Agility, the ability to move quickly or alter di-rection as scenarios change;
• Cost-effectiveness, the ability to reduce cost per unit benefit by re-optimizing a mix of assets;
• Competition, the ability to motivate alternative options to be better or discourage monopolies or oligopolies from extracting large rents;
• Specialization, an ability for each to concentrate on comparative advantage, reducing any need to compromise those advantages to compen-sate for its own disadvantages;
• Differentiation, the ability to signal different messages more clearly;
• Diffusion, an ability to force those who would threaten to divide their resources to solve mul-tiple problems;
• Robustness, an ability to withstand pressure by spreading it around; and
• Resilience, the ability to cope with error by hav-ing alternative options.
Trades between simplification options and diversi-fication options can be made, but ultimately the ques-tion becomes: “What is the determining measure of merit?” Is it “more bang for the buck?” Less “sticker shock” per warhead? More stability per resource
ex-strategic power has begun with more simplicity be-cause of limits on knowledge and resources. Bombs on aircraft are the classic first step. Nevertheless, the quest for diversity is sometimes seen very early—the Manhattan Project developed both a uranium gun as-sembly and a plutonium implosion device. Most nu-clear powers move to greater diversity over time, but some have reduced diversity as security improves, numbers go down, or budgets become tight. This in-cludes the United States.
Still, more than any other country, the United States has emphasized diversity in its approach to strategic stability, including technology. Why? A number of causes seem active. The first is capability. The United States is big. It has resources. It is a strategic leader and has extended responsibilities. The United States has a dynamic technology culture including numer-ous defense corporations. It has “think tanks,” interest groups, and activists asking “What if?” It has democ-racy and debates that invite a “marketplace of ideas.”
All of these can create pressure for diversity. In the end, however, the primary drivers of diversity for the United States have been the strategic convictions that, in working to prevent nuclear war, (1) more op-tions are necessary because one size does not fit all, (2) change is inevitable, as is surprise, and (3) the conse-quences of failure could be tragic.
A few words of caution are in order about strate-gies employing diversity. Investors who pay multiple fees for mutual funds that contain mostly the same se-curities are not as diversified as they think, and even very different assets may be subject to the same mar-ket forces. The same is true of technologies associated with strategic stability. Different strategies, forces, organizations, operations, and technologies can have
common modes of failure. For example, aircraft and submarines have very few bases, all soft. ICBMs and SLBMs could someday face highly effective missile defenses. All components are dependent on commu-nications ultimately from the National Command Au-thority (NCA).
TECHNOLOGY AND THE HUMAN FACTOR