Carlos Pascual, the U.S. ambassador to Mexico, served as vice president and director of the Foreign Policy Program at Brookings from 2006 to 2009. Before joining Brookings, he served with the U.S. Department of State and was U.S. ambassador to Ukraine, 2000-03. He also was special assistant to the president during the Clinton administration and worked with the National Security Council from 1995 to 2000.Jonathan Elkind, who is now the principal deputy assistant secretary for policy and international energy at the U.S. Department of Energy, was a nonresident senior fellow in the Foreign Policy Program at Brookings from 2006 to 2009. An expert in energy security, the environment, Eastern Europe, and the former Soviet Union, he was on the National Security Council staff between 1998 and 2001. He also served in a variety of other government positions during the Clinton administration.