A move has been made:
The correct response now would be for NATO to send troops into Crimea (or even other territories currently controlled by Russia). Otherwise makes it all about who controls the new disputed territories, with Russia only with territory to gain but no territory to lose, placing it into an advantageous position from the outset.
If someone starts punching you on the street and your "fighting back" consists only of blocking, you are not really fighting back. You are only seriously fighting back when you successfully make the aggressor feel that they could lose more than they stand to gain.