BERLIN — Veteran German diplomat Helga Schmid, a key behind-the-scenes negotiator of the 2015 nuclear accord with Iran, was named Friday as the new administrative head of the Organization for Security and Co-operation in Europe.

The Vienna-based regional security organization plays an important role in trying to resolve conflicts in Europe and on its periphery, including Ukraine. Its 57 members include Russia and the United States.

A career diplomat, the 59-year-old Schmid was the German embassy's spokeswoman in Washington during the early 1990s, before taking senior roles at the German Foreign Ministry in Berlin, and later moved to Brussels. She spent the last four years as the head of the EU's diplomatic service.

The post of OSCE secretary general comes with a three-year term that can be renewed once. The secretary general is the administrative head of the OSCE, complementing the presidency which rotates annually among member states.

A branch of the organization also conducts election monitoring missions, including during last month's U.S. presidential vote.