In his diplomatic career, Ambassador Kmentt has worked extensively on disarmament and non-proliferation issues, including as Deputy Permanent Representative of Austria to the Conference on Disarmament in Geneva and as Special Assistant to the Executive Secretary in the Preparatory Commission of the Comprehensive Nuclear Test-Ban Treaty Organisation and from 2011-16 as Director of the Department for Disarmament, Arms Control and Non-Proliferation at the Austrian Ministry for Foreign Affairs; a position which he resumed in 2021. From 2016-19, Kmentt served as Ambassador and Permanent Representative to the Political and Security Committee of the EU.