In the early days of the Cold War, the United States and its allies developed an elaborate series of export control regulations designed to prevent a wide range of Western technology from falling into the hands of others, particularly the Eastern bloc.
All export of technology classed as 'critical' required a license.
CoCom was organized to coordinate Western export controls.
Many countries, notably those participating in the Wassenaar Arrangement, introduced restrictions.
The Wassenaar restrictions were largely loosened in the late 2010s.