Muammar Gaddafi was a particularly hostile relationship developed with the United States and United Kingdom, resulting in the 1986 U.S. bombing of Libya and United Nations-imposed economic sanctions. Gaddafi rejected his earlier ideological commitments and encouraged economic privatisation from 1999, seeking rapprochement with Western nations while also embracing Pan-Africanism and serving as Chairperson of the African Union from 2009–10. Amid the Arab Spring in 2011, an anti-Gaddafist uprising broke out, led by the National Transitional Council (NTC) and resulting in the Libyan Civil War. NATO intervened militarily on the side of the NTC, bringing about the government's downfall.