So you obviously must think neither Finland nor Austria nor Japan have been sovereign since WWII since none of them were armed much at all and each could have been easily smacked down by any major power.
Your being ridiculous at this point, Putin has stated clearly multiple times Ukraine should not exist. He has repeatedly taken territory from it. Somehow a disarmed Ukraine would be protected from further Putin annexations, even though you yourself have stated Putin could invade again. Japan is a large island nation, suggesting the US was going to absorb it is ludicrous. The Fins are armed to the teeth and will probably join NATO, so I’m not sure why you keep bringing up these not relevant examples.