The very idea of it is fraught with geopolitical tension for just that reason. As it stands, NATO membership comes with the implication that the US and Western

The very idea of it is fraught with geopolitical tension for just that reason. As it stands, NATO membership comes with the implication that the US and Western Europe will respond to any invasion with their full force, up to and including strategic nuclear warfare if needed. Russia would surely see the very proposal to include Ukraine as intensely threatening. It could be a giant bluff in a way - would we dare to include Ukraine, knowing how deeply it threatens Russia? Would Russia dare to do anything direct about it, like a preemptive invasion, maybe before they were a full member? If they did, would we respond, drawing ourselves into a large war, or ignore it, potentially diluting the meaning of NATO and tempting Russia to try invading other NATO members as well? Would Russia respond vigorously but indirectly, essentially starting a new Cold War?