We should start airlifting Ukrainian troops deployed abroad back to Ukraine. And prepare to send humanitarian aid to Ukraine given the unsettled situation there.
Looking back at our response to Putin's invasion of Georgia--which didn't involve going to war with Russia, I'll add--we should work with Ukrainians and start airlifting Ukrainian troops (fewer than 500) from around the globe back to Ukraine. do it all very publicly.
And send a Coast Guard ship or two with humanitarian supplies to Odessa, for use in Crimea.
And is Mount Whitney still in the Black Sea? That ship should be intercepting every Russian transmission she can and sharing useful (and safe for us to reveal) with the Ukrainians. And satellite photos, too, of Russian troop movements.
Could we set a meeting between Ukraine's government and a private military company that could help plan Ukrainian military operations?
I am certainly not suggesting we should go to war with Russia over this crisis. But we should do what we can to deter Russia from taking too much if we can't deter them from seizing parts of Ukraine.
UPDATE: I remain focused on military operations in Crimea because I still think Russia's military is not capable of fighting more than a small war--or nuking you.
Moving 25,000 paratroopers and internal security troops into Crimea to back the 3,000 naval infantry and 10,000 other military personnel already based in Sevastopol seems within Russia's capabilities.
If Russia operates in eastern Ukraine, I think it would be more of a road march and attempt to occupy ground without trying to fight, portraying the movement as an effort to protect pro-Russian civilians.
So Ukraine should not assume that they can't defeat a small Russian war within Ukraine.