That is certainly not true. From the article itself: “which Israel had purchased from Boeing with Israeli funds”. So they do buy with their own money. But far less then I assumed.
What I missed was that the US provides aid, with the caveat that Israel has to spend it on US weapons. So they are buying from the US, but with US money.
I’ll second the importance of core for avoiding back pain. I do mostly abs focused core workouts and that helps a lot for me personally.