The survivability of the United States’ land based offensive nuclear forces has never been a given, but it is becoming more precarious. Both Russia and the People’s Republic of China (PRC) are engaged in comprehensive nuclear modernization programs that have likely made their nuclear missiles more accurate, improving both states’ capabilities for attacking hardened structures with pinpoint accuracy—their “hard-target kill” capabilities. In its comprehensive review of the U.S. Strategic Posture, the bipartisan Commission on the Strategic Posture of the United States recommended that policy leaders consider basing a portion of the future land-based intercontinental ballistic missile (ICBM) force in a road-mobile configuration, enhancing deterrence against more capable adversary threats to ICBM survivability. This is not the first time the United States has undertaken efforts to address improving adversary counterforce capabilities, and those cases offer important lessons about the value of missile defenses in a balanced strategic posture. Given these qualitative advances in Russian and Chinese capabilities to threaten the ICBM leg of the U.S. nuclear triad, U.S. defense policy makers should explore the possibility of deploying missile defense systems to defend its ICBM fields. Blasts from the Past In the early 1970s, President Richard Nixon became increasingly concerned about the Soviet Union’s expanding counterforce capabilities. The size of the Soviet ICBM arsenal grew rapidly and overtook the U.S. ICBM, and it also began deploying new systems, like the SS-9, that could carry multiple re-entry vehicles (MRVs) and were believed to be far more accurate than older Soviet ICBMs. This development led the Department of Defense (DOD) to recommend the Safeguard Anti-Ballistic Missile (ABM) system, which was designed to provide active defenses for U.S. Minuteman ICBMs. While DOD considered alternative methods of bolstering ICBM survivability—including mobile ICBMs— defense officials ultimately concluded that an ABM system would likely be less expensive. Nixon moved to deploy Safeguard, hoping that an ABM system would provide him a valuable bargaining chip in the Strategic Arms Limitation Talks (SALT) with the Soviet Union and a strategic hedge if the talks failed. In the wake of the SALT Interim Agreement with the Soviet Union, Congress scrapped Safeguard in 1975 because it deemed the system unnecessary and too costly, given SALT. In the late 1970s, the threat to U.S. ICBMs became more acute. While SALT had slowed the development of U.S. nuclear forces, the Soviet Union surged forward with quantitative and qualitative enhancements to its arsenal, shifting the strategic balance in the Soviets’ favor. It developed multiple independently-targeted re-entry vehicles (MIRVs), more capable and accurate than older MRV systems, and it deployed a heavy ICBM, the SS-18, that could carry between 8-10 MIRVs. This prompted President Jimmy Carter’s administration to reconsider the utility of active missile defenses for enhancing fixed silo survivability. Later, President Ronald Reagan convened the Scowcroft Commission to provide recommendations on strategic forces. The Commission tackled, among other issues, the growing vulnerability of the U.S. ICBM force, but it concluded that ballistic missile defense (BMD) technology was likely not mature enough to defend fixed, hardened silos against a large number of warheads. While Cold War-era defense officials recognized that BMD systems designed to defend specific points, as opposed to large geographic regions, were plausible options for defending the U.S. ICBM force, these proposals failed because they relied on immature technology and were too pricey. In today’s strategic environment, however, those barriers no longer exist. The Case for Point Defense Today Today, there is a completely different technological picture for missile defense. The success of terminal-phase missile defenses on battlefields in Ukraine and Israel demonstrate that BMD in regional contexts is now feasible. Advances in remote sensing, paired with artificial intelligence-enabled data analysis, have made missile defense easier and more affordable by enabling more effective fire control, higher responsiveness, and more reliable kill assessments. The political picture has also changed. Whereas BMD was once an issue championed exclusively by one political party, it has gradually become more mainstream. In 1999, Congress passed the National Missile Defense Act of 1999, which called for the deployment of a national missile defense system as soon as it would be technologically feasible, passed by an overwhelming, bipartisan margin. Now there is an emerging bipartisan consensus that supports more expansive missile defense deployments; the bipartisan Strategic Posture Commission recommended that the United States deploy more advanced integrated air and missile defense capabilities to address the coercive threats posed by Russia and the PRC. Deploying point defenses around ICBM fields would also enhance the U.S. nuclear posture by enhancing the survivability of ICBMs. The U.S. nuclear triad contributes to deterrence because each leg—air, land, and sea—is, on its own, survivable and capable of holding at risk key adversary targets. When the three legs of the triad are combined, they create a capability that is greater than the sum of its parts, and the triad enables the president to have a flexible range of capabilities he or she can use to deter the United States’ adversaries. However, the survivability of each leg also enables the U.S. to hedge against technical breakthroughs that could render one, or both, of the other legs vulnerable. A sudden advance in anti-submarine warfare could, for instance, leave U.S. ballistic missile submarines, currently the most survivable leg of the triad, vulnerable to counterforce targeting, so the other two legs of the triad must each be survivable and capable of deterrence without it. Active defenses would therefore strengthen the United States’ overall nuclear posture by making the ICBM leg more resilient. Furthermore, active defenses around ICBM fields would enhance deterrence. While it is unlikely that either Russia or the PRC would launch a large-scale strike on U.S. ICBM fields, that likelihood is a function of an adversary leader’s belief that the strike would be successful, as failing to eliminate the ICBM force would invite devastating retaliation. Introducing active missile defenses would therefore create uncertainty in the minds of adversary decisionmakers, decreasing the likelihood they would execute such a strike. Engendering such uncertainty is of paramount importance, given the threat of opportunistic or coordinated aggression from Russia and the PRC—conflicts that would likely be lengthy and involve the attrition of some U.S. nuclear capabilities, elevating the relative value of the remaining forces. Importantly, existing Ground Based Interceptors deployed in Alaska and California are insufficient for this task because they are designed to intercept incoming targets outside of the atmosphere, which can be difficult because of decoys and penetration aids. Active defenses for ICBM fields, however, could be designed to intercept incoming targets later in flight, after decoys and penetration aids have burned up upon entering the atmosphere. Alternative measures to enhance the survivability of the ICBM force are potentially both prohibitively expensive and will come too late. Deploying the future Sentinel ICBM in a road-mobile configuration is unlikely to cost less than the Sentinel program, and road-mobile missiles might require novel designs or the diversion of funds within the defense budget from other essential priorities like conventional munitions procurement. Moreover, the United States’ nuclear enterprise is already struggling to simultaneously modernize all strategic weapons and delivery systems in the current arsenal, and adding a road-mobile transporter-erector launcher to the fray will likely exacerbate delays. Missile defense systems, however, could be procured independently from the nuclear enterprise, and they would help advance budgetary priorities. The Missile Defense Agency has reportedly investigated the utility of using Terminal High Altitude Area Defense (THAAD) systems for homeland defense against incoming reentry vehicles in their terminal phase. While THAAD has a relatively limited coverage footprint, it can intercept incoming targets within the atmosphere, which gives it a leg up against decoys and penetration aids because most will burn up upon entering the atmosphere. Importantly, the THAAD supply chain is currently under less stress than other weapons systems in use in Ukraine and the Red Sea. However, the U.S. is planning to deploy a THAAD battery to Israel, and THAAD is already an essential component of the defense of Guam. Buying munitions in greater quantities tends to decrease each munition’s individual price because it sends a strong demand signal to the defense contractor responsible for manufacturing it; by procuring additional THAAD batteries and interceptors for the defense of U.S. ICBM fields, DOD would send a strong demand signal to the defense industry, which could decrease the cost of procuring the capability in the medium-term. Opponents of national missile defense have argued that it has potential to exacerbate arms racing and contribute to crisis instability. While these criticisms are not typically leveled against point defenses, opponents could plausibly argue that point defenses would contribute to the same dynamics. First, the connection between missile defenses and arms racing is dubious because it does not align with the historical record. Indeed, after the U.S. and the Soviet Union agreed to limit ABM systems by signing the ABM Treaty in 1972, the Soviet Union accelerated its efforts to quantitatively and qualitatively enhance its strategic arsenal. Second, crisis instability exists when one side perceives that the other might try to start a nuclear war and use its defenses to ride out the conflict without incurring an unacceptable level of damage. However, point defenses around ICBM fields would not contribute to crisis instability because they would not be capable of limiting damage to the American population in a nuclear exchange; they would only defend missiles that would, presumably be used or destroyed in a general nuclear war either way. Thus, a limited deployment of missile defenses around ICBM fields would be unlikely to affect arms race dynamics and would not contribute to crisis instability. A Path Forward The emerging multi-adversary nuclear environment and the respective Russian and PRC qualitative counterforce improvements present a serious challenge for U.S. nuclear strategy. This is not a novel challenge, however, as U.S. decision makers faced analogous situations in both the early and late 1970s, respectively. In the 1970s, the Nixon, Carter, and Reagan administrations all considered using local missile defenses to defend ICBMs, but these proposals did not pan out because of political challenges and immature technology. The emerging bipartisan consensus on missile defense and the development of defensive technologies now present an opportunity to use active defenses to offset the Russian and PRC challenges to the U.S. ICBM force. Deploying these active defenses would enhance the U.S. strategic posture, strengthen deterrence, and provide a foundation for future missile defense enhancements to defend other elements of U.S. nuclear forces and command and control.