The only preventative measures which would've worked would be diplomatic and economic counter-pressure from the UN and more specifically Europe and other NATO allies, or substantial military build up capable of seriously endangering US conventional forces.
Ukraine would be in a much different military position today if it were a pariah state, as opposed to a nation declaring a strong intent to join both the EU and NATO. Turns out diplomacy, allies and soft-power are actually kind of useful things when you're not the dominant military hegemon.
Spoiler: it has never worked. What you are thinking of are diplomatic, economic and military moves and counter-moves or negotiated settlements but the aggressor is always forced to compromise or delayed such that they lose their advantage.
Appeasement - the aggressor making demands and getting them with the idea that they will be then be satisfied - has never worked.