“Doesn’t anyone remember how defense of Europe works?”
Considering how Russia just waltzed into Ukraine and took what it wanted, looks like American leadership doesn’t remember how defense of Europe works.
I expect both Russia and China will make massive land grabs within a few months, betting that the Obama has no interest in defending anyone. They’ll make the move while the disinterested lame duck is in office, and start soon enough that they’ll have it all wrapped up, under control, and defenses firmly in place before 20 January 2017.
Ukraine isn't a NATO nation, and we still conduct military exercises in Ukraine, and if you notice, the invasion of Ukraine is destroying Putin, and is rebuilding, uniting, and reinvigorating NATO, and may even enlarge NATO, as Sweden and Finland start looking at joining.