On April 5, 2009, President Obama articulated a vision of a nuclear-free world in a speech in Prague, marking the start of a committed pursuit of enhanced global nuclear security. He reiterated this commitment in a June 2013 speech in Berlin, but while significant progress has been made, many aspects of this agenda have stalled or failed to get off the ground. Five years after the speech in Prague, it is time to revitalize the cause of nuclear security and non-proliferation. The “Prague Agenda” laid out in Obama’s 2009 speech focuses on several steps to reduce the threat of nuclear weapons—reduction of the number of nuclear weapons within states that already possess them; reduction of the role of nuclear weapons in national defense; prevention of nuclear proliferation by strengthening the global non-proliferation regime and punishing those states in violation of their obligations; securing vulnerable nuclear materials and enhancing international cooperation on nuclear security; and Senate approval of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). Progress toward these goals has been made, albeit unevenly. A litany of factors, including political obstruction from domestic opposition and worsening ties with Russia, has prevented more extensive progress from being realized. Moreover, the White House has not always pursued these goals with the vigor required of such an ambitious agenda. To sustain progress on this front, Obama must advance the Prague Agenda more forcefully throughout the remainder of his second term. The New START Treaty, which came into effect on February 5, 2011, supported the first item on the Prague Agenda—to reduce the world’s supply of nuclear weapons, starting with the United States and Russia. In his Berlin speech last year, Obama announced that the United States would pursue a reduction in the number of deployed strategic nuclear weapons by up to a third, bringing the total from the 1,550 allowed under New START closer to 1,000. As part of an update to high-level nuclear weapons policy guidance, this proposed reduction and further changes to the US nuclear posture would reduce the role that nuclear weapons play in US defense policy. However, the administration is predicating further reductions in the number and role of nuclear weapons on a negotiation with Russia, which Russia refused. Cooperation is especially unlikely to deepen amid the crisis in Ukraine and allegations that Russia violated the Intermediate-Range Nuclear Forces Treaty (INF). With regards to the global non-proliferation regime, Obama has gone to great lengths to strengthen the regime, most obviously seen through his commitment to a negotiated settlement to the Iranian nuclear impasse. Yet despite recent progress on Iran, North Korea’s nuclear weapons program continues to expand. The 2010 Non-Proliferation Treaty (NPT) Review Conference yielded consensus on a final document, a notable achievement given the failure to arrive at such a conclusion in 2005. The document espoused specific action designed to strengthen the three pillars of the NPT, non-proliferation, disarmament, and peaceful use of nuclear energy. On non-proliferation, a variety of proposals were put forward, many of which have seen progress since 2010--for example, strengthening export controls and encouraging states to adopt the NPT Additional Protocol. On disarmament, the final document requires nuclear weapons states to report on their disarmament activities at the 2014 NPT Preparatory Committee meeting in late April and for the first time explicitly states that the goal of the NPT's disarmament provision is a world free of nuclear weapons. Other action plan items, such as negotiations on a Fissile Material Cut-off Treaty and on a nuclear-weapons-free zone in the Middle East have stalled, and realistic steps toward nuclear disarmament post-New START have been few and far between. The United States under President Obama deserves great praise for leading a global effort to secure vulnerable nuclear materials. Through the Nuclear Security Summit, Obama has ensured that this issue has remained at the forefront of the international community’s agenda, and a great deal of measurable progress has been made in reducing the amount of vulnerable nuclear material around the world. Beyond the planned 2016 Nuclear Security Summit, however, it is unclear how the United States will pursue global nuclear security. Furthermore, budget cuts have slowed the pace of nuclear security efforts, and many projects have been delayed or place on hold indefinitely. Finally, the CTBT still has not been ratified despite Obama’s insistence in Prague that his administration would “immediately and aggressively pursue U.S. ratification of the Comprehensive Test Ban Treaty.” Five years after Obama established an ambitious commitment to nuclear security and non-proliferation at Prague, his record on the subject remains mixed. While progress has been made in some areas, many initiatives have stalled. To make matters worse, the Russian incursion in Ukraine will be a major obstacle to political cooperation between the United States and Russia, but there are steps the administration can take that need not rest on immediate Russian reciprocity. The fifth anniversary of the Prague speech provides the administration with a chance to intensify its efforts in support of nuclear security and non-proliferation.