The United States — preoccupied with the wars of the Middle East and a pivot to Asia — has largely left the global playing field to Russian President Putin and must now lead NATO by forging a new consensus on the Russian threat and investing in new weapons. The correlation of forces in the European theater has arguably not been this favorable for Russia since the end of the Cold War. The ability of U.S. and NATO forces to deter Russian aggression is declining and is, arguably, dangerously close to the threshold of acceptable risk in the Baltic States. The United States must now lead the NATO alliance by forging a new consensus on the threat and investing in new capabilities to address the operational problems created by Moscow’s military modernization. This will require a combination of a significantly fortified force posture, increased prepositioning of equipment, special forces to build partner capacity and deter gray zone aggression, and most importantly, a counter to Russia’s maturing integrated land, air and maritime anti-access area denial (A2/AD) capabilities. While the European Reassurance Initiative (ERI) constitutes the most significant reinforcement of NATO’s force posture since the end of the Cold War, a single armored brigade combat team, even supported by NATO air and sea power, does not mark a meaningful shift in the military balance. We need additional forces to reinforce NATO’s position and they should be armed with medium- and long-range artillery and, perhaps, short-range ballistic missiles to deal with the operational challenges of Russia’s A2/AD “bubble.” Developing a capability to counter Russia’s highly developed skill set in information warfare remains another urgent requirement for the United States. Russia’s activities in this domain are based on a view of war that sees propaganda, disinformation and “active measures” as part of a range of activities that include operations in the electro-magnetic spectrum, including sensors and jammers, and cyber operations. Russia’s efforts in this arena today are wielded with a sophistication that far surpasses the Soviet Union’s ham-handed Cold War agitation and propaganda. Despite the potentially dire consequences on the battlefield of not counteracting these measures, the United States has not yet developed an effective or comprehensive riposte to Russia’s deft use of these tools. Russia’s across-the-board nuclear modernization underscores the need for a robust U.S. nuclear triad as a deterrent, especially in light of U.S. treaty guarantees to provide its allies with the shelter of an American nuclear umbrella. While Russia has prioritized the modernization of its entire nuclear arsenal, the United States is only beginning to face the challenges of replacing the aging systems that make up its nuclear forces. The calculated ambiguity of Russian doctrine over nuclear weapons use, and Putin’s nuclear saber rattling pose a major challenge for NATO. How can the US maintain and reinforce NATO’s nuclear deterrent mission? One relatively easy step would be to include additional allies, like Poland, in that mission. Another might be to respond to Russian violations of the INF Treaty by starting research and development on a new Pershing III intermediate range ballistic missile. In addition to those steps, Congress must consider repealing the Budget Control Act. Ending what we all call sequestration would give the U.S. sufficient budgetary resources and a reasonable planning horizon to counter Russia’s current advantages in the conventional balance of forces along its border. Without lifting these budget restrictions, the United States will find itself handicapped in trying to meet the challenges that Russia’s revanchism poses to European security. Lastly, the United States should take advantage of Russia’s reliance on oil and gas exports. The energy windfall between 2003 and 2014 allowed Moscow to fund the overhaul of its conventional and nuclear forces. The United States should use its developing energy self-sufficiency to keep energy prices low, limiting Russia’s ability to funnel discretionary funds into military investments. Increased gas production and export of liquefied natural gas also will give American allies in Europe alternatives to Russian energy supplies and deny Moscow opportunities for blackmail and political influence. The United States has a number of options for countering and limiting Russian aggression but U.S. policymakers have grown accustomed to a Europe that has been largely free of the major security challenges that characterized the Cold War. Today, defending Europe demands greater attention from policy makers and more resources than it has since the Cold War ended. Unless the U.S. takes steps to reverse the unfavorable trends of the past few years, the result is likely to be a less stable and less prosperous Europe.