U.S. operations supporting the Mujahedeen in Afghanistan against the Soviets were conducted almost entirely from and through Pakistan.
Notes on verification
Well-corroborated by multiple independent sources including academic/military analysis (West Point CTC), historical overviews, and Wikipedia's detailed account of Operation Cyclone, all confirming Pakistan (via ISI) as the near-exclusive conduit for CIA support to the Mujahideen.
Sources
- Special Warfare: The Missing Middle in U.S. Coercive ... (warontherocks.com)
- https://ctc.westpoint.edu/comparing-the-u-s-and-soviet-experiences-in-afghanistan/ (ctc.westpoint.edu)
- https://courses.lumenlearning.com/suny-hccc-worldhistory2/chapter/the-united-states-and-the-mujahideen/ (courses.lumenlearning.com)