The invasion was ill-conceived strategically, however, it MAY be possible that 2000 troops could occupy a planet as long as they had orbital and air support. It helps that Vulcan probably dismantled most if not all it's own military force after it joined the UFP. Unfortunately such an invasion would be untenable in the face of UFP reinforcements.
It's very likely that a company of US Army troops from 2012 could defeat a German division from WWI...a period of roughly 94 years. We're talking 24th century technology, almost 400 years in the future...with a rate of change that is moving even faster than previous eras.