Putin strongly objected to U.S. Pres. George W. Bush’s decision in 2001 to abandon the 1972 Anti-Ballistic Missile Treaty. In response to the September 11 attacks on the United States in 2001, he pledged Russia’s assistance and cooperation in the U.S.-led campaign against terrorists and their allies, offering the use of Russia’s airspace for humanitarian deliveries and help in search-and-rescue operations.