After having worked in the United Nations Office for Disarmament Affairs on transparency of armament capabilities, military spending, and disclosure of military information (2007-2014). Kryvonos has a long career in disarmament-related work at United Nations agencies as he has also worked in the field of security and cooperation at the The Organization for Security and Cooperation in Europe (OSCE)Conflict Prevention Center (2001-2007) and as First Secretary at the Permanent Mission of Ukraine to the United Nations in Vienna, where he was responsible for security areas including nuclear disarmament and nonproliferation.