Following his honorable discharge from the Army at the rank of captain, Napper attended the University of Virginia from 1972 to 1974, earning a master's degree in government and foreign affairs.

After a year of Russian language training, Napper was assigned to the United States Embassy in Moscow, where he served as Vice Consul from 1975 to 1977.

In 1983–84, Napper received an American Political Science Association Congressional Fellowship in the office of Representative Lee H. Hamilton.

In 1984, Napper returned to Embassy Moscow for a two-year assignment as Chief of the Foreign Affairs Unit of the Political Section.

After six months of Romanian language training, Napper became Chargé d'affaires and later Deputy Chief of Mission of the U.S. Embassy in Bucharest, Romania from 1989 to 1991.