> placing a large US business interest in Ukraine (as opposed to backdoor dealings) is actually a way of strengthening the US's commitment and investment in Ukraine, right?

If the US is not willing to militarily defend it, it doesn't mean anything. Russia can just take the land, and cut a deal with the US to let them extract there for some time.

A security guarantee or NATO membership would be an effective deterrent to further conflict, but Trump doesn't want it.