No thanks to the United States, NATO, or western European heads of government, the Ukrainian army actually seems to be cleaning the clock of Putin's surrogates in eastern Ukraine. To be sure, some of this is being done by ad hoc militaries financed by "oligarchs," in a manner reminiscent of the messy wars of the 1920s in the same part of the world. But still! With no American help but a long-ago shipment of Meals Ready to Eat, the government in Kiev seems to have reconstituted an army in a matter of weeks, and that army is actually fighting. Kiev now claims to have gained control of its border with Russia, so as to stop or anyhow slow the influx of mercenaries, war materiel, and probably Russian special forces operatives.
Still, even the best outcome will have been a victory for Vladimir Putin in his attempt to recreate the Russian Empire that was lost in 1917 (and again in 1991!). Nobody in Washington, Brussels, or Berlin is now going to invest any of the west's much-diminished moral force in trying to get the Russians out of Crimea. That train has left the station, and probably even the government in Kiev will be willing to let Crimea go, rather than risk further confrontation with the bully in the Kremlin.
Then too, Putin has succeeded in destabilizing and radicalizing a good chunk of the country. Civil wars always radicalize the population. From now on, Kiev will live in fear of what the Russian bear can do, and the same is true of other countries (Estonia being a prime example) unfortunate enough to share a frontier with Russian, and to contain large numbers of people who not only claim Russian as their mother tongue, but hold Russian passports. The mere threat of proximity is what enabled the Soviet Union to control the foreign policy of Finland for the better part of half a century, 1940-1990.
And in a wider sense, Putin has the rest of Europe by the short hairs. NATO famously was formed to "keep the Americans in, the Russians out, and the Germans down." Well, the Germans are no longer down, and the Americans under Barack Obama are no longer in, so what's to keep the Russians out as long as they are the ones providing natural gas to western Europe?