In the 1950s, Yugoslavian scientists began to consider uranium enrichment and plutonium reprocessing. During the '50s and '60s, Yugoslavia and Norway cooperated on plutonium processing. A fuel reprocessing site and research reactors were built for which the Soviets provided heavy water and enriched uranium. In 1966 plutonium reprocessing tests began.
For unknown reasons President Josip Tito froze the nuclear program in 1960. When India, Yugoslavia's rival for the leadership of the non-aligned movement, conducted its first nuclear tests in 1974, Tito restarted Yugoslavia's nuclear program in order to compete.
After Tito's death in 1980 the nuclear program continued but limited financial resources brought it to an end in 1987, according to the Nuclear Threat Initiative. The country has never produced a nuclear weapon.