It's not the first time it happens. For example, in 2006 the US stopped supplying spare parts to F-16s it sold to Venezuela.[0] Oddly, other countries kept buying F-16s.
Or think about Boeing and Airbus stopping servicing the planes they sold to Russia. Other countries are still buying from them as if nothing happened.
The difference is that now European countries, and other (former?) US allies are starting to see the US as a threat. With people like Trump in power, the chance of a military conflict between the EU and the US is now non-zero, so what's on everyone's mind going forward will be independence from US tech. Maybe you haven't seen European news and commentary.
US's republicans still don't grasp what a diplomatic mess Trump is causing, which will surely affect all trade. Actually, I'm expecting consequences for the entire US tech sector, not just the defence sector.
Or think about Boeing and Airbus stopping servicing the planes they sold to Russia. Other countries are still buying from them as if nothing happened.
[0] https://www.foxnews.com/story/venezuela-threatens-to-sell-f-...