Yes. The idea was to keep the engines (and engineers) out of the hands of the other likely buyers. You've seen how soviet military surplus gets around: the same channels work for rocket engines, and those engines work in ICBMs just as well as they work in orbital launch platforms.

I don't know how effective this was. Did it backfire by promoting economies of scale in a program that went on to sell to adversaries anyway? Did it murder the domestic engine programs and did that have knock-on consequences? I don't know if the policy was effective, but I do know that stopping "engine proliferation" was a widely given and accepted reason for those programs.

Interestingly, Ukraine has a lot of space industry and relevant experience. The EU could make use of that, one day. Or the Western world in general.

Of course that means not leaving them over to the bear.

Indirect through ULA, but yes; it's not like Russia is in an alien dimension. Trading with it was fine, at least until recently.

Every engine that america was buying from Russia was not ending up in China. Massive national defense win.

> Given that ULA historically purchased engines from Russia, are you suggesting that it was a direct mechanism for transferring tax revenue to Russia companies?

I mean, for many years the US bought seats on Soyuz launches, so that was an even more direct mechanism.

Yes. Deliberately so. They wanted to ensure that rocket and nuclear technology did not proliferate in the 2000s and were willing to directly pay for Russian engineers and knowledge to keep them from going elsewhere.