The United States has 123 Agreements with almost all countries with major nuclear energy programs. A glaring exception is Russia, a country with one of the most technologically advanced and commercially active nuclear industries in the world. The reasons for this anomaly include the mutual mistrust that prevailed during the Cold War, the dormancy of the U.S. nuclear industry in the post-Cold War period, and the differing approaches of the two countries toward the nuclear fuel cycle. Since the mid-1990s, the main impediment to a U.S.-Russia 123 Agreement has been Russian nuclear assistance to Iran, which the United States believes is pursuing a nuclear-weapons capability under the cloak of a civil nuclear program. In an effort to induce Moscow to end such assistance, the Clinton administration and initially the Bush administration refused to negotiate a 123 Agreement with Russia unless it halted all nuclear cooperation with Iran, including its construction of a nuclear power reactor at Bushehr. However, at the July 2006 meeting of G-8 leaders in St. Petersburg, Presidents George W. Bush and Vladimir Putin announced that bilateral negotiations would begin. The talks proceeded smoothly and an agreement was signed in Moscow on May 6, 2008. On May 13, the White House transmitted the 123 Agreement and its supporting documentation to the Congress for its consideration. The U.S.-Russia agreement meets all the legal requirements set forth in Section 123 of the Atomic Energy Act. In particular, it contains all the required nonproliferation guarantees and controls, including a U.S. right of prior consent to retransfers, a guarantee that adequate physical protection measures will be maintained with respect to U.S. exports, and a guarantee that no U.S.-origin nuclear material will be enriched or reprocessed without the prior approval of the United States. A 123 Agreement can give the U.S. leverage with the Russians. But the leverage, and the ability to influence Russian behavior, comes not from withholding U.S. approval of the agreement; it comes from implementing the agreement and giving the Russians a tangible, vested interest in continuing to cooperate with the United States. Critical U.S. nonproliferation objectives, especially the goal of preventing Iran from acquiring nuclear weapons, cannot be achieved without the active cooperation of Russia. The best way to gain that cooperation--on Iran and a wide range of other issues--is to bring the U.S.-Russia 123 Agreement into force at an early date.