I worked for Norden Systems on radars in the 80’s and early 90’s. I mentioned this at a subsequent job to a Russian coworker and he said what a coincidence I commanded a radar installation in Vietnam. I said ‘The Russians were in Vietnam? “He sputtered and tried to back out of the statement. I told him to lighten up. We were both just doing what our government told us to do.
There were Soviet pilots flying MiGs in both Korea and Vietnam.
Excellent way to gain combat experience for their pilots.