In 1968 he joined the diplomatic corps of the UN, where he was appointed head of the documentation services of the general secretariat for Europe and America from 1987 to 1992.

Among other positions in the high body, he has been the personal representative of the Secretary-General of the United Nations in the peace processes of El Salvador and Nicaragua (1989–1991), Guatemala (1990–1992) and East Timor (1999).

[3] In 1999 he was appointed head of the UN Secretary-General's Office for Political Affairs in Asia, the Pacific, America and Europe.

From 2000 to 2002, he headed the UN special mission to Afghanistan (UNSMA), and was later appointed representative of the European Union.

Afterwards, he worked as an adjunct professor at the School for Advanced International Studies (SAIS), Johns Hopkins University, Bologna campus.