Global Security Review analysis by Richard Purcell (Jan 23, 2020) Editor’s note: This is the second piece in a two-part
Editor’s note: This is the second piece in a two-part series examining the role of damage limitation strategy in U.S. nuclear war planning. Read part one here.
With the apparent reemergence of great power competition in recent years, the possibility of military conflict with a nuclear-armed adversary has rekindled old debates about the role that damage limitation should play in U.S. nuclear planning.
Nuclear damage limitation involves reducing the U.S.’s vulnerability to an adversary’s nuclear weapons. It is a warfighting capability intended to enable the United States to prevail in a nuclear conflict, should one arise. There are a number of ways to achieve damage limitation, but most discussions of this topic focus on two in particular: neutralizing an adversary’s nuclear missiles before they can be fired, generally known as counterforce, and intercepting incoming missiles after they have been launched but before they reach their targets.
Current American policy states that damage limiting capabilities are an important component of the nation’s overall strategic posture. The most recent U.S. Nuclear Posture Review, released in February 2018, asserts that if U.S. strategic forces fail to deter an enemy attack, the U.S. “will strive to end any conflict at the lowest level of damage possible and on the best achievable terms for the United States, allies, and partners. U.S. nuclear policy for decades has consistently included this objective of limiting damage if deterrence fails.” It adds that “U.S. missile defense and offensive options provide the basis for significant damage limitation” in the event of a nuclear conflict.
The Pentagon’s Missile Defense Review, issued in January 2019, echoes this approach. It affirms that in the event of a conflict, the United States would seek “to prevent and defeat adversary missile attacks through a combination of deterrence, active and passive missile defenses, and attack operations to destroy offensive missiles prior to launch.”
These official assertions are a far cry from the long-held conventional wisdom among U.S. civilian leaders that, as Ronald Reagan once put it, “a nuclear war cannot be won and must never be fought.” Maintaining some damage-limitation capabilities, as the United States has always done, is sensible in that it provides U.S. policymakers with flexibility in the event of a nuclear crisis. However, emphasizing damage limitation as a primary element of U.S. strategic posture carries considerable risk. Damage limiting capabilities may seem like prudent investments in self-protection by a nation that adopts them, but rival nuclear powers tend to see them as threatening and provocative. While such capabilities do have the potential to reduce the costs of a nuclear war, they also increase the likelihood that one will occur.
There are two main arguments in favor of emphasizing damage limitation. The most obvious is that it enhances the U.S.’s ability to defend itself and its allies if a nuclear war happens. Damage limitation proponents believe that since there is always a possibility that nuclear deterrence will fail, it would be irresponsible for the United States to forego nuclear warfighting capabilities. They contend that if a conflict were to arise, damage limiting options would be necessary to minimize a nuclear-armed opponent’s ability to impose unacceptable costs on the United States.
The second argument for damage limitation is that it enhances extended deterrence by strengthening the credibility of U.S. security commitments to its allies overseas. These commitments, which are intended both to deter aggression by hostile actors and reassure American allies of U.S. support, may seem uncertain if the attacking nation possesses nuclear weapons. Other countries, both friends and foes, might reasonably question whether the United States could be counted on to intervene on an ally’s behalf if its adversary had the ability to destroy American cities.
Nuclear-armed opponents would not need to have a nuclear arsenal as powerful as that of the United States to deter American military intervention. They would only need the ability to credibly threaten to inflict more costs on the United States than Washington would be willing to bear. Crisis outcomes often turn on the question of which side possesses greater resolve. Superior resolve corresponds to greater acceptance of risk, and in a crisis or conflict, the side that is more risk-tolerant has a significant advantage. It can credibly threaten to escalate—or, if need be, actually escalate—to a point where the danger of an unacceptable outcome for the opposing side exceeds its willingness to contest the first side’s actions.
Advocates for emphasizing damage limitation see it as a way to compensate for a perceived lack of American resolve. Any U.S. confrontation with a nuclear-armed adversary would take place far from American shores. The adversary, being much closer to the scene, would likely believe that it cared more about the confrontation’s outcome than the U.S., and it might well be correct in making such an assessment. (For instance, it is generally recognized that in the event of a crisis or conflict over Taiwan, the outcome would matter much more to China than it would to the U.S.) As a result, the adversary might be more willing to take escalatory actions that risked a nuclear exchange than would the U.S., giving it an advantage in any brinkmanship contest.
According to damage limitation proponents, this advantage would be negated if the United States possessed sufficiently effective damage limiting capabilities. Such capabilities would reduce the costs the U.S. could expect to incur if a nuclear conflict did happen and would, therefore, weaken a hostile nuclear power’s ability to deter the U.S. from intervening on behalf of an ally. If U.S. allies and potential enemies both believed that the United States could substantially reduce its nuclear vulnerability, then the credibility of U.S. extended deterrence would be greatly enhanced—or so goes the thinking.
One of the specific ways the U.S. has sought to use damage limitation to strengthen extended deterrence is by deploying a variety of missile defense systems. Some of these systems are likely more effective than others. The conventional wisdom is that the longer the range of the inbound missile, the more difficult it is to shoot down. U.S. continental missile defenses have demonstrated a fifty percent success rate in testing over the last decade, but the tests have been highly scripted and have not simulated actual wartime conditions. In addition, the system relies on an array of radars and other sensors located in space and on the ground that would be vulnerable to attack.
It’s unclear what perceptions in Washington and foreign capitals would be regarding the effectiveness of U.S. strategic defenses if push came to shove. It does seem fair to say that for the foreseeable future, the system will be unable to provide anything approaching “leakproof” protection to the U.S. homeland against even a modest-sized nuclear attack. As a result, nuclear plans that emphasize damage limitation require extensive capabilities for neutralizing an opponent’s weapons before they can be employed.
There is significant debate within the national security community about the potency of U.S. counterforce capabilities. Current U.S. nuclear delivery systems are generally accurate enough to destroy an adversary’s nuclear forces if their locations can be determined. However, North Korea, Russia, and China all possess mobile, land-based missiles which could be difficult to find, particularly during a crisis when they would likely be dispersed and concealed in order to increase their survivability. In order to execute an effective counterforce attack, the U.S. would also need to overcome an enemy’s efforts to disrupt the U.S.’s ability to locate, track, and destroy the correct targets in a timely manner. Nonetheless, some modern observers contend that U.S. intelligence, reconnaissance, and surveillance capabilities have become so advanced that launching a disarming first strike against an opponent is a realistic option.
The main problem with emphasizing damage limitation in U.S. nuclear war planning is that it undermines stability and risks making nuclear war more likely. While it is theoretically true that damage limitation options may enhance stability by strengthening deterrence, this assumes that a crisis or conflict would necessarily occur as a result of large-scale aggression by an adversary. It further assumes that potential U.S. opponents see nuclear weapons primarily as tools for coercion or aggression. Many American observers fail to appreciate the fact that hostile regimes genuinely fear the United States.
While the U.S. views China, Russia, and North Korea as potential aggressors, these nations likewise view the United States as a serious threat. The latter two appear to view it as an existential one. In all three cases, the primary purpose of their nuclear forces is to deter a U.S. nuclear attack and, in the cases of North Korea and Russia, a conventional one as well. Failing that, they could utilize their nuclear arsenals to either deny the U.S. the ability to achieve its objectives or impose sufficiently high costs on it that it feels compelled to cease its military operations.
This is not to deny that nations like North Korea, China, and Russia have revisionist aims. Rather, it is to point out that belligerent actions on their part would likely stem from more than just a sudden desire for conquest or expansion. A crisis or conflict could arise because of an accident, misunderstanding, or because a low-level confrontation led to unanticipated escalation (for instance, the United States and North Korea nearly came to blows in August 1976 over the removal of a poplar tree in the Korean Demilitarized Zone). Under such circumstances, an adversary could make undesirable decisions that are motivated less by greed or conquest than by fear of U.S. intentions. While American damage limiting capabilities might be useful for deterring the former, they can also contribute to the latter.
In the context of an international security crisis between two nuclear powers, the concept of stability pertains to the likelihood of nuclear escalation. Crisis stability is high when neither side has an incentive to initiate the use of nuclear weapons against its opponent. Typically, this condition is met when both sides possess a significant number of nuclear weapons that can survive an opponent’s first strike and be used for retaliation. Thus, when the state of affairs is characterized by mutual deterrence, stability is enhanced.
Crisis instability is high when one or both sides possess capabilities that allow them to threaten the opponent’s ability to retaliate. In a period of heightened tensions, the risk of war would already be significantly higher than during normal peacetime conditions. If the chances of war seemed high enough, each side would likely perceive there to be advantages in engaging in nuclear first use and disadvantages in not doing so, even if there were significant asymmetries between the two sides’ arsenals. The side with larger nuclear forces would have an incentive to mount a counterforce first strike before its opponent could employ its nuclear weapons. The side with the smaller arsenal would be incentivized to go nuclear early, before any of its nuclear forces could be destroyed. In this way, U.S. emphasis of counterforce in its nuclear planning would greatly undermine stability during a crisis, something that is highly undesirable.
U.S. strategic missile defenses would also exacerbate crisis instability. Most knowledgeable observers believe that these systems would only be partially effective at best. The smaller the inbound attack, the more effective they would be. In a security crisis in which the likelihood of nuclear conflict seemed high, this situation would further incentivize striking first. A counterforce first strike by the U.S. would reduce the number of missiles the adversary could launch against U.S. targets, making the task of American missile defenses more manageable. The adversary, in turn, would have an incentive to launch its missiles before that could happen, knowing that a larger first strike against the United States would have a better chance of overwhelming U.S. defenses than would a smaller retaliatory one.
The Missile Defense Review is fairly clear that it envisions U.S. counterforce strikes occurring after an adversary engages in first use. This is consistent with the U.S. claim that the primary purpose of its nuclear arsenal is to deter nuclear attacks against it and its allies. However, the United States also publicly reserves the right to initiate the use of nuclear weapons if it believes circumstances warrant it. American counterforce options could easily be employed in a first strike backstopped by U.S. missile defenses, and potential adversaries may well conclude that they are intended for this purpose.
If the goal is to limit nuclear damage, a U.S. counterforce attack would make much more sense as a first strike rather than as an act of retaliation. It’s unclear what circumstances would prompt the U.S. to take such action. In the early stages of an emergent security crisis, the risk of nuclear escalation would seem low. This would reduce the impetus for a U.S. first strike, since no rational American leader would want to start a nuclear war that could be avoided. At the same time, the effectiveness of a U.S. counterforce attack would likely be higher near the beginning of a crisis than it would be later on, since the adversary would almost certainly take steps to improve its arsenal’s survivability as the crisis intensified. This would incentivize an early U.S. preemptive strike, especially since American leaders would know that the opponent might resort to nuclear escalation anyway even if the U.S. initially exercised restraint.
The effectiveness of U.S. damage limiting capabilities in a shooting war would be highly uncertain. Conflicts rarely unfold in ways that conform to pre-war expectations, new weapons do not always work as anticipated, and the fog of war can never be completely eliminated. A nuclear counterforce attack has never been attempted in human history, and no missile defense system has ever been used in action against a large-scale missile attack. These considerations alone should raise questions about the wisdom of emphasizing damage limitation in U.S. nuclear planning.
This uncertainty about the effectiveness of U.S. damage limitation capabilities creates the worst of all possible worlds. In a crisis or conventional conflict, the possibility that the United States could launch a disarming first strike would incentivize first use by the adversary, as described above. However, recognition on all sides that no damage limitation system could ever be 100 percent effective would limit damage limitation’s contribution to extended deterrence because Washington would likely view the risk of just one American city being destroyed as intolerable.
Deemphasizing damage limitation in U.S. nuclear war planning would enhance crisis stability without undermining extended deterrence. Global perceptions about the strength of U.S. security commitments are informed by a number of factors, including U.S. policy declarations, conventional military power, the strength of its alliances, and its ability to respond in kind to an adversary’s first use. It’s worth noting that even though the Soviet Union was capable of inflicting enormous devastation on the United States during the Cold War, Washington was still able to deter Moscow from attacking vital American interests, despite the fact that the U.S. possessed only a modest damage limiting capability.
Fears that a hostile nation might view its ability to launch nuclear attacks against the U.S. homeland as a license to engage in aggression are also not supported by historical evidence. The last 75 years have demonstrated that nuclear weapons are not terribly useful for achieving offensive aims that seek to alter the status quo. They are, on the other hand, extremely useful in deterring an adversary from engaging in first use. Even if the United States altered its strategic posture to deemphasize damage limitation, its nuclear arsenal would still constitute a potent deterrent to any nation contemplating nuclear escalation. As a result, an adversary of the United States would be unlikely to initiate the use of nuclear weapons unless it believed it had no other choice.
Fundamentally, the debate over whether or not U.S. nuclear policy should emphasize damage limitation is between those who believe the United States should possess the ability to win a nuclear war and those who prioritize the stability of mutual deterrence. This is an argument that dates back to the 1960s when the Soviet Union first began to approach nuclear parity with the United States. Many nuclear experts hold views that lie somewhere between these two perspectives.
The truest believers in damage limitation tend to be individuals who hold hawkish views about U.S. foreign policy in general, and they have been influential under the Trump administration in setting U.S. nuclear policies. They see damage limitation as a trump card that can negate an opponent’s ability to deter the United States with nuclear weapons. In reality, a damage limiting strategy will never be possible to fully eliminate U.S. vulnerability to nuclear attack, and efforts to enhance the U.S.’s ability to fight and win a nuclear war only serve to make such a conflict more probable. Avoiding that outcome should be the overriding goal of U.S. nuclear planning.