The West appears to have underestimated the strength of the Kremlin’s negative reaction toward NATO’s eastward expansion. Russia’s reluctant acquiescence to the Baltic states’ joining the Atlantic alliance was clearly misleading: Moscow did make some noise, but it was in no position to take any active measures of resistance, as Russia back then was still relatively weak.
For the Kremlin, the establishment of a NATO foothold in Georgia would be an intolerable development that could spark a domino effect across the Caucasus. It would start with the internationalization of peace process in Abkhazia and South Ossetia, causing Russia to lose its monopoly on "peacekeeping" operations, and culminate with Moscow losing control over the South Caucasus - with the grave consequences for stability in Russia’s volatile North Caucasus autonomous republics. To prevent this from happening, the Kremlin "preempted" the Western move and, in a risky gambit, radically changed the situation on the ground.