LONDON (AP) âÄî The United States and Russia set a newly ambitious course for global cooperation Wednesday as presidents Barack Obama and Dmitry Medvedev ordered negotiators into immediate action on a treaty to further reduce nuclear weapons. Going into their first face-to-face meeting in London, Medvedev had voiced openness to Obama’s call for resetting the deeply troubled U.S.-Russian relationship, but few had expected the kind of sweeping statements that emerged from weeks of intense preparatory talks. While setting in motion fast-track negotiations on a replacement for the seminal 1991 Strategic Arms Reduction Treaty, or START, which expires at year’s end, the two leaders vowed at the same time to jointly confront other perceived threats. They specifically mentioned the nuclear programs in Iran and North Korea and al-Qaida militants who have found refuge in Pakistan. They set a nominal July deadline for a substitute treaty for START, a date that coincides with Obama’s first presidential visit to Russia. That conceivably would leave time to get the new treaty approved in the U.S. Senate by the December expiration of the current agreement. But arms control experts say December is not a hard deadline so long as there is progress. Sen. Richard Lugar, the Indiana Republican devoted to arms control, said the announcement of intent was “truly remarkable.” Not known for overstatement, Lugar called the joint declaration “almost breathless in its optimism and scope.” He spoke in an interview with MSNBC. Obama’s engagement with the Russians marks a stunning reversal from policies of the Bush administration, which was disinclined to take up deep arms control negotiations and had angered Moscow with its intention to install a missile defense system in Poland and the Czech Republic. Russian Foreign Minister Sergei Lavrov drove that point home in a briefing with Russian reporters after the Obama-Medvedev meeting. “The new atmosphere of mutual trust,” he said, is meaningful in “taking into account mutual interests and readiness to listen to each other.” He added, “We missed this much in the past years.” The joint statements are a major boost for both Obama and Medvedev âÄî both new to the foreign policy proving grounds and in need of the other’s help. If Medvedev is successful, with Obama, in midwifing the birth of a new nuclear reduction treaty, the Russian leader will solidify his hold on Kremlin power, where former President Vladimir Putin âÄî now the prime minister âÄî is perpetually looking over the shoulder of his hand-picked successor. Obama stands to gain a major ally in the foreign policy problems most vexing to his administration, particularly Iran, Afghanistan and North Korea. Obama sweetened the deal for the Russians by pledging to work for the U.S. ratification of the Comprehensive Nuclear Test Ban Treaty, something that long has been high on the Russian agenda. Moscow has ratified the test ban pact, but the United States has not, nor have four other members of the nuclear club: China, India, Pakistan and Israel. The new U.S. president also said he would put his shoulder behind Russia’s bid for World Trade Organization membership, a key to Moscow’s integration into the global trading system. In return, the Russians put Iran on notice that it “needs to restore confidence in its exclusively peaceful nature.” Washington contends the Iranians are using work on a civilian nuclear program for electricity generation as a cover for weapons development. Moscow retains significant sway with Tehran. On Afghanistan, the joint documents talk of solving the ongoing conflict in a “regional context,” which was believed to signal Russia’s readiness to help. Moscow also agreed to toughen its tone on North Korea, with the statement saying the Stalinist country’s plans for a missile launch would be “damaging to peace and stability in the region.” Moscow joined Washington in urging Pyongyang to “exercise restraint and observe relevant U.N. Security Council resolutions.” Obama and his aides were particularly pleased about the Russian position on Iran and on agreement about the threat from extremists in Afghanistan and Pakistan. But the talks were not all about agreement. Last August’s devastating war between Russia and the former Soviet republic of Georgia came up, with Obama saying directly that Georgia’s pro-Moscow separatist regions of South Ossetia and Abkhazia would never be recognized as independent by the United States, U.S. officials said. Speaking for the Russians on American missile defense plans in Central Europe, Lavrov voiced the expectation that Moscow’s concerns could be eased in the coming talks on a treaty to replace START. Going into the new nuclear talks, the United States had 2,200 strategic nuclear warheads deployed; Russia has 2,800. Under the subsequent 2002 Treaty of Moscow, a plan negotiated under the Bush administration, the two sides committed to reducing their nuclear warheads to between 1,700 and 2,200. But that treaty did not establish its own system for verifying compliance; instead it said verification would rest upon the existing provisions of the START treaty. But if START expires in December without a replacement in place, the Moscow Treaty would be left with no legally binding system for verification. Obama has declared his belief that the United States and Russia should take the lead in ridding the world of nuclear weapons altogether. Russian and American arms control experts believe that the START replacement treaty would seek initially to cut strategic warhead arsenals to 1,500 on each side. ___ Steven R. Hurst reported from Washington; Associated Press writer Barry Schweid contributed from Washington.