'X' was a communist revolutionary. He served as the President of his country from 1953 to 1980. He was one of the founding members of the Non-Aligned Movement. 'X''s country was made up of six republics - Bosnia and Herzegovina, Croatia, Macedonia, Montenegro, Serbia, and Slovenia. This country no longer exists in the form that it used to, with the constitutent republics having declared independence in the years after 1991.
Identify 'X'.