During the tour of Ambassador Beyrle in Moscow, there was a notable improvement in the tone of Russian-American relations. The United States and Russia signed the START-2 agreement on the reduction of nuclear weapons, as well as agreement on the peaceful uses of nuclear energy, and an agreement reducing visa restrictions and providing better monitoring of adoptions. After 15 years of negotiations, Russia finally became a member of the World Trade Organization. Russia permitted the United States to supply its armed forces in Afghanistan via air and land transit. Russian law enforcement agencies began cooperating more regularly with the U.S. Department of Homeland Security, the Drug Enforcement Administration, and the Federal Bureau of Investigation. The U.S. military carried out several joint military exercises with the Russian military, and U.S. aircraft took part in the Moscow air show. For the first time U.S. soldiers participated in the parade on Red Square marking the anniversary of the end of World War II. Although serious differences remained over missile defense, the occupation of Georgian territory and human rights, the political relationship was less confrontational than it had been in previous years.