US President Barack Obama said he and Russian President Dmitry Medvedev are countering "a sense of drift" in relations between their nations with preliminary agreement Monday to reduce the world's two largest nuclear stockpiles to as few as 1,500 warheads each. "We must lead by example, and that's what we are doing here today," Obama said as he and his Russian host pointed their arsenals toward the lowest levels of any US-Russia arms control agreement. "We resolve to reset US-Russian relations so that we can cooperate more effectively in areas of common interest," Obama said. The document signed by the two leaders at a Moscow summit, Obama's first in Russia, is meant as a guide for negotiators as the nations work toward a replacement pact for the START arms control agreement that expires in December. The joint understanding completed by Obama and Medvedev, signed after about three hours of talks at the Kremlin, also commits the updated treaty to lower longer-range missiles for delivering nuclear bombs to between 500 and 1,100. The limit for warheads would be no more than 1,675 each. Medvedev called it a "reasonable compromise." Under current treaties, each country is allowed a maximum of 2,200 warheads and 1,600 launch vehicles. A White House statement said the new treaty "will include effective verification measures" and Obama said definitively the new treaty would be completed by the end of the year. "The new agreement will enhance the security of both the US and Russia, as well as provide predictability and stability in strategic offensive forces," the statement said. The two leaders appeared together at a news conference in a gilded and columned Kremlin hall, where they and other officials from both countries signed and exchanged documents with great flourish and much handshaking. Among the deals meant to sweeten Obama's two days of talks here and show progress toward resetting badly damaged US-Russian relations was permission from Moscow for the United States to transport arms across its land and airspace into Afghanistan for the war there. The White House said the deal will save the US $133 million a year, by waiving transit fees and shortening flying time. They outlined other areas in which they said their countries would work together to help stabilize Afghanistan, including increasing assistance to the Afghan army and police, and training counternarcotics personnel. A joint statement said that they welcomed increased international support for upcoming Afghan elections and that they were prepared to help Afghanistan and Pakistan work together against the "common threats of terrorism, extremism and drug trafficking." Among other side agreements was the resumption of military cooperation, suspended after Russia invaded neighboring Georgia last August and sent relations into a nosedive. The White House announced that the two nations plan 20 exchanges and meetings this year. For example, Russian military cadets will come to the US Military Academy at West Point. The two countries also plan a joint exercise concerning responses to possible plane hijackings. They also promised new cooperation on public health issues and revived a joint commission to try to account for missing service members of both countries dating back to World War II. The commission was first created by the first President Bush and President Boris Yeltsin in the early 1990s, but the Russians later downgraded their participation. The US hope is that the Russians will now open some of their more sensitive archives to US researchers seeking details about missing American servicemen. Yet, the two sides remain stalemated over the US pursuit of a missile-defense system in Europe, pushed hard by Bush and under review by Obama. Both sides hardened their positions before the summit. The US contends the program is designed to protect US allies in Europe from a potential nuclear attack by Iran. But the Russians see it as a first step toward a system that could weaken their offensive nuclear strike potential. Obama needs Russia's help chiefly in pressuring Iran and North Korea to give up their nuclear weapons ambitions, but also in tackling terrorism, global warming and the economy. But with Russia's public wary of America and ties frayed over Moscow's war in Georgia and the missile defense plan, Obama's desire to move forward is a huge test of his diplomatic skills. "The president and I agreed that the relationship between Russia and the United States has suffered from a sense of drift," he said at Medvedev's side. "President Medvedev and I are committed to leaving behind the suspicion and rivalry of the past." His host expressed similar good will. "This is the first but very important step in improving full-scale cooperation between our two countries, which would go to the benefit of both states," the Russian leader said.