> Look and Georgia and Ukraine know -- both these countries started in a similar position as we after the breakup of USSR, the key difference was that they haven't joined NATO and/or EU.
Semi-seriously: Ukraine at least had a treaty securing its borders by the US, UK, and Russia. If the US and UK aren't willing to act on that treaty, what makes one think they'd act on a NATO Article V invocation by them if they were NATO members?
Because not invoking NATO Article V would immediately render the whole alliance useless (as this article is the whole point of NATO) and I'm sure no member of it would risk that. Russia pulling a similar trick as in Ukraine on any NATO member without serious consequences would be an achievement comparable to the victory of the Cold War.
Semi-seriously: Ukraine at least had a treaty securing its borders by the US, UK, and Russia. If the US and UK aren't willing to act on that treaty, what makes one think they'd act on a NATO Article V invocation by them if they were NATO members?