This will turn out to be a mistake for Putin.
Russia has a lot of advantages in a conflict with Ukraine. But it also has a lot to lose if it poisons its relationship with Europe and the rest of the world. Putin might get away with it if he confines military action to the Crimea (after all, this intervention is allegedly at the request of the Crimean regional government's request for Russian assistance--a request it only made after pro-Russian gunmen took control of the regional government's parliament and other buildings). But as Josh Marshal points out, the Russian parliament has approved military intervention in "Ukraine," not just the Crimea.
Russia has a lot of advantages in a conflict with Ukraine. But it also has a lot to lose if it poisons its relationship with Europe and the rest of the world. Putin might get away with it if he confines military action to the Crimea (after all, this intervention is allegedly at the request of the Crimean regional government's request for Russian assistance--a request it only made after pro-Russian gunmen took control of the regional government's parliament and other buildings). But as Josh Marshal points out, the Russian parliament has approved military intervention in "Ukraine," not just the Crimea.