Jaap de Hoop Scheffer has been appointed professor of international politics at the University of Leiden, the university said in a statement released on Thursday, according to dpa. The former secretary general of NATO is to start his new position, which is limited to three years, on September 1. On July 21, De Hoop Scheffer, 61, underwent treatment in a hospital in Brussels after suffering from a minor blood clot. The Christian Democrat served as secretary general of NATO from 2003 to 2009. He has previously served as Dutch foreign minister (2002-03) and as chairman of the Christian Democrats in the Dutch parliament (1997-2001).