[jjoonathan]

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.

[m4rtink]

Well, RD-180 is not really a suitable engine for modern ICBMs due to the need for a cryogenic oxidizer, resulting in the ICBM not being a very responsive design. But you are certainly correct about the engineers.

[jjoonathan]

Good point. Still, I have to imagine that the engines themselves are dual use in some regard. GNSS or spy satellites maybe? These days it seems like everyone and their dog has a GNSS constellation, but it wasn't always that way.