I believe it was purely for reasons of expansion. I don’t know exactly what our response should have been, but we need to at least acknowledge that Ukraine is defending their sovereignty and Putin/Russia are the aggressors. We should support them at least minimally.
Of course Russia uses conscription as well. In fact don’t most countries that go to war use conscription? I don’t like it but, if we can stop it here then the next country that Russia might invade wouldn’t have to draft soldiers.