U.S.-Russian bilateral nuclear arms control is about to collapse. For decades, these two countries have used formal treaties to regulate the nuclear balance between them. Currently they are parties to two such treaties. The most recent is the New START Treaty, limiting deployed strategic warheads to 1,550 on each side. New START was signed in 2010, entered into force in February 2011 and will expire in February 2021. Despite the current tension in U.S.-Russian relations (which is probably as bad as any time since the Cuban Missile Crisis) implementation is going smoothly. New START is often considered a bright spot in the relationship. Unfortunately, that is about to change. Things will change because of concern over the second treaty, the 1987 Intermediate Range Nuclear Forces Treaty (INF Treaty), which bans ground-launched ballistic or cruise missiles with ranges between 500 and 5,500 kilometers. In 2014, the United States formally accused Russia of testing a ground-launched cruise missile in violation of the INF Treaty. To protect intelligence sources, the United States released no details but asserts that it has provided Russia with sufficient information to identify the violation. Russia has denied any violation, claimed the information provided by the United States is insufficient for evaluation, and expressed concern in turn over three potential American treaty violations. In March of 2017, the vice chairman of the Joint Chiefs of Staff testified to Congress that the prohibited missile had been deployed. While the INF violation is intrinsically important, this analysis focuses on the impact of the dispute on the future of the far more important strategic nuclear arms treaty. When New START was signed, it was assumed that it would be followed by a replacement treaty that would further lower weapons levels and deal with issues omitted from New START. Without solving the INF issue, it will be both inappropriate and politically impossible for the United States to negotiate such a replacement. Any such treaty could not be ratified by the U.S. Senate. As a result, when New START expires in 2021 the United States will face a situation where, for the first time in half a century, no treaty regulating the nuclear balance between Russia and the United States will be either in force or under negotiation. In theory, the two governments could delay this outcome. New START allows for a single, five-year extension without the need for ratification. Such an extension would not be a panacea. While there are straightforward ways to resolve Russian concerns with U.S. compliance with INF, resolving U.S. concerns appears unlikely, especially since Russia refuses to even acknowledge them. Without a solution to INF, an extension only postpones the demise of bilateral arms control. But an extension would buy time to plan for a future with no formal bilateral arms control agreements. Unfortunately, President Trump appears to have rejected such an extension, which also faces strong political opposition in Congress. While the United States should work toward an extension, analysts also need to assess how to limit the damage to political and strategic relations between the United States and the Russian Federation if New START expires with no plans for replacement. Because arms control is not an end in itself, but a means to ensure national security and international stability, the first step is to analyze the specific problems the end of the treaty will cause. For the United States, one problem is the loss of transparency and predictability, which enhance stability. For Russia, bilateral arms control symbolizes the respect and equality that the country expects and deserves. For both, the New START Treaty demonstrates compliance with Article VI of the Nuclear Non-Proliferation Treaty and helps preserve the international non-proliferation regime. Both sides have a policy of maintaining rough strategic parity with one another; strategic arms control allows them to do this without reigniting an arms race. There are doubtless other benefits that further analysis will reveal. After understanding the specific benefits of New START, the two governments should jointly consider how, if at all, they can mitigate the consequences of its lapse. They might, for example, continue exchanging periodic data on strategic forces as a confidence building measure. They might have an informal agreement that neither would expand above New START levels provided the other side showed comparable restraint. To show they can cooperate on a basis of respect and equality, Russia and the United States might intensify cooperation under the Global Initiative to Counter Nuclear Terrorism, which the two sides co-chair. A joint initiative to help states comply with UN Security Council Resolution 1540 and a parallel initiative to revitalize discussions on controlling fissile material would provide modest signals of support for the nonproliferation regime and Article VI. These ideas are obviously rudimentary. More thinking, discussion and analysis is needed. A possible official forum for such activity is the recently-resumed U.S.-Russian strategic stability discussions. Official dialogue should be supplemented by informal, track 2 efforts. But the prerequisite for any discussion is sound and creative internal analysis The prospect of the demise of bilateral arms control is a gloomy one. But the problem will not be improved by ignoring it. The era of Russian-American strategic arms control is coming to an end. It may not be possible to prevent that, but thinking through the consequences can minimize the harm to U.S.-Russian relations, to international stability, and to the cause of peace. That thinking should begin now.  According to the State Department’s 2017 arms control compliance report, that information includes Russia’s internal designator for the mobile launcher chassis, the names of the companies involved in developing and producing the missile and launcher, the test history, including coordinates of the tests and Russia’s attempts to obfuscate the nature of the program.