Following the Velvet Revolution and the breakup of Czechoslovakia in 1993, he decided to stay with the newly formed Slovak Ministry of Foreign Affairs.

[1] Under his leadership the Fund gained significant recognition in the four respective nations and rapidly increased in size.

Rusnák served as the extraordinary and plenipotentiary ambassador of the Slovak Republic to Ukraine from 2005 to 2009.

[3] Rusnák is a lecturer and author of professional articles on the topics of international relations, energy security and development.

[6] He was chairman of the editorial board of the Slovak Institute for International Studies (2000–2003), editor in chief for the MFA International Issues Journal (1998–1999) and is on the editorial board of the Slovak Foreign Policy Association.