From 1973 to 1975, Ischinger served on the staff of the Secretary General of the United Nations in New York. He joined the German Foreign Service in 1975, and has served in Washington, D.C., Paris, and in a number of senior functions in the German Foreign Office. From 1993 to 1995, Ischinger was director of the Policy Planning Staff under Foreign Minister Klaus Kinkel; from 1995 to 1998, as director general for political affairs (political director), Ischinger participated in a number of international negotiating processes, including the Bosnia Peace Talks at Dayton, Ohio, the negotiations concerning the NATO-Russia Founding Act, as well as the negotiations on EU and NATO enlargement and on the Kosovo crisis.