A clear U.S. policy toward Russia should include sanctions in response to Russia’s annexation of Crimea, its continued military intervention in Ukraine, and its meddling in U.S. and European elections. The absence of painful and sustained costs would prompt Putin and his leadership coterie to conclude that they have little to fear from Washington and its allies, as long as there is the thinnest patina of deniability. At the same time, however, the United States should clarify for Moscow what actions it can take (or avoid taking) over a given period of time to achieve relief from sanctions. Unconditional—or poorly conditioned—sanctions would leave Russia with little incentive to alter threatening behavior.

In addition, the United States should respond with military deployments to Russia’s violation of the Intermediate-Range Nuclear Forces (INF) Treaty. This should include strengthening America’s nonnuclear long-range strike capabilities in Europe and supporting its partners’ efforts to do so as well. Washington should also work with NATO allies to continue to improve missile defenses in Europe. It should make clear that EPAA deployment, along with other missile-defense capabilities, will have a role in deterring Russia’s use of missiles in Europe, while reaffirming that EPAA deployments in Romania and Poland will still be unable to engage Russian ICBMs aimed at the United States. The U.S. response to Russia’s INF violation should further include the deployment of a follow-on to the Tomahawk Land Attack Missile–Nuclear (TLAM-N), built with stealth features based on the Long-Range Standoff (LRSO) nuclear cruise missile. This follow-on to TLAM-N would fill a deterrence gap by adding a survivable and credible theater nuclear deterrent that complements dual-capable fighter-bombers (potentially vulnerable both to preemptive attacks on air bases and to advanced air defenses) and dual-capable long-range bombers (the use of which, if in response to theater use of nuclear weapons by Russia, would require the United States to be the first to engage in homeland-to-homeland nuclear strikes).

Finally, the United States should continue to develop areas of cooperation with Russia. Washington will need Russian support for (or abstention on) further U.N. Security Council–imposed sanctions on North Korea, and likely other threats to international peace and security that come before the council in the future. The two might productively cooperate in some areas of the Arctic, in civilian space activities, in diplomatic negotiations over Syria’s future and in the Global Initiative to Combat Nuclear Terrorism, which Russia and the United States cochair. Even as American leaders continue to press a modest, positive agenda, they should put greater priority on deterring bad behavior and avoiding a slide toward crisis and conflict.

THE UNITED States should take additional steps to mitigate the potential for attacks in cyberspace and outer space to trigger rapid, uncontrolled escalation. One of the first steps should be to define its desired rules of the road for cyberspace and outer space, not only in peacetime, but also in crisis and conflict. It should then seek consensus with key allies and partners, with whom a common understanding of preferred guidelines for offensive cyber and outer-space activities remains lacking. Armed with an allied consensus, Washington should test the degree to which arriving at a common view with Moscow (and, likely separately, Beijing) is possible. Even if the United States and Russia fail to reach a common view, well-prepared bilateral discussions regarding rules of the road in cyberspace and outer space would help clarify where various actions might fall on the escalation ladder, thereby reducing the risk that either side unwittingly takes actions viewed by the other as extremely threatening.

Next, following a framework offered in a Defense Science Board Task Force report on cyber deterrence, DOD should bolster cyber and space resilience for critical military capabilities in three ways. First, it should ensure the cyber and space resilience of the nuclear triad, and the “thin line” of NC3 systems that supports it even in a nuclear exchange. Second, the department should ensure the essential cyber and space resilience to support a select but substantial subset of nonnuclear long-range strike capabilities, such as the new B-21 bomber and JASSM-ER and attack submarines equipped with conventional Tomahawk cruise missiles. Having punishing nonnuclear strike options available for response even after withstanding the other side’s best efforts at cyber and space attacks would significantly decrease the incentive to conduct such an attack, without requiring the president to escalate to a nuclear response. Third, DOD should ensure that select offensive cyber (and, if applicable, offensive counterspace) capabilities are highly resistant to both cyber and counterspace attacks, so that the United States may respond in kind to an attack limited to cyberspace and outer space.

The United States should also improve the digital resilience of its critical infrastructure. A focused national effort sustained over a period of many years could fundamentally reduce the cyber vulnerability of at least the most essential U.S. critical infrastructure, including the electrical grid, key elements of the financial sector, water and wastewater systems, and the electoral system. There will be no quick fixes, but with strong leadership from both the public and private sectors, the United States could substantially reduce the digital vulnerabilities of select portions of its critical infrastructure over the next ten to twenty years. By addressing these vulnerabilities, Washington can reduce Russia’s incentives to attack and the potential escalatory impact if it does so.

In addition—and critically—the United States should reopen diplomatic and military lines of communication with Russia. These channels are crucial for reducing the risks of miscommunication and avoidable conflict. Notwithstanding how difficult U.S.-Russian relations are today, the United States should work to reopen channels of communication, including diplomatic as well as military-to-military ones. Some initial steps—for example, tactical deconfliction in Syria—have taken place already, but much more is needed.

JUST AS the integration of a range of new technologies is undermining strategic stability, so too is an integrated program necessary to buttress strategic stability between the United States and Russia in the coming years and decades. This program must consider changes in both nuclear and nonnuclear systems, and in both nuclear and nonnuclear strategies.

As a first step in such a program, the United States should adopt a “triad-plus” strategic force structure. This means proceeding with the Columbia-class strategic submarine modernization program, B-21 dual-capable bomber program, and LRSO missile program. It also means that, rather than pursuing a one-for-one replacement of Minuteman III ICBMs in underground silos, the United States should develop a replacement ICBM that is significantly lighter than the Minuteman III and deploy perhaps two or three hundred of the missiles in silos. The United States should also initiate a mobile ICBM research-and- development program, including prototypes, so that the United States can shift weight to a mobile ICBM force in the event of a Russian breakthrough in antisubmarine warfare (ASW). Remanufacturing a stealthy version of the TLAM-N would also allow the United States to hedge against Russian ASW improvements.

At the same time, the Department of Defense should address vulnerabilities in NC3 systems and review launch-under-attack postures. DOD should invest first in ensuring that its nuclear forces and NC3 are highly resilient to a top-tier cyber adversary. Next, both the U.S. and Russian leadership must understand the reality that their NC3 systems could suffer some degradations in crisis or conflict—some of which may not be due to attacks by the other side; a third party might attempt a false-flag operation. Accidents and acts of nature can also cause service disruptions of some systems. Both sides should ensure that their planning and exercises account for such events. Finally, the U.S. and Russian postures to be prepared to launch ICBMs under attack deserve careful review, so as to minimize the risk of launching on false warning. How both sides can adjust their postures to this effect remains difficult to say. It is important to note, however, that the more the United States hedges through other means (e.g., TLAM-N and mobile ICBMs) in the future, the less pressure there will be to launch ICBMs under the warning of attack.

As the United States proceeds with a program of nuclear modernization, it should also develop and deploy nonnuclear hypersonic weapons, tailored to defeat major improvements in the air-defense systems of potential U.S. adversaries. The United States should aim for a “sweet spot” for nonnuclear hypersonic weapons in terms of military effectiveness (high), cost (relatively low), potential for high-volume strikes (significant) and impact on strategic stability (low). Medium-range ballistic missiles (with and without boost-glide vehicles) and hypersonic cruise missiles, launched from heavy bombers and/or attack submarines, could fall in this sweet spot. The systems would have a low impact on strategic stability because their infrared and other signatures would be substantially different and distinguishable from those of U.S. nuclear-delivery systems (including SLBMs and nuclear-tipped cruise missiles), attacks on one nation would not require overflight of others, and these systems would either lack the range to attack deep into Russia (the case for submarine-based medium-range systems) or would be unable to do so in volume without creating a massive detectable signature (the case for bomber-based systems).