Hill, an assistant secretary of state, is seen as somewhat of a surprise choice as ambassador because he doesn't speak Arabic and his expertise is in Europe and Northeast Asia, The Washington Post reported Tuesday.
He was ambassador to Poland, Macedonia and South Korea and also was a top negotiator to the Dayton peace accords that ended the Bosnian war in the mid-1990s.
Hill succeeds Ryan C. Crocker, who retired in January. Hill would be the fourth U.S. ambassador to serve in Iraq since the fall of Saddam Hussein and the establishment of an Iraqi government.
Working on behalf of the United States, and with negotiators from Japan, Russia, China and South Korea, Hill led talks with North Korea over abandoning its nuclear weapons ambitions. Hill persuaded the North to shut down and disable its nuclear reactor, culminating with the North blowing up the reactor's cooling tower before a worldwide audience in June. Talks since have soured.