"We have fashioned these sanctions to impose costs on named individuals who wield influence in the Russian government and those responsible for the deteriorating situation in Ukraine," the White House said in a statement. A senior administration official said that the goal of the sanctions was to target the individual wealth of the seven people targeted by Monday's executive order. But those same officials would not rule out further steps against the Russian government going forward.
(This quote comes from http://www.nbcnews.com/storyline/ukraine-crisis/obama-announces-new-sanctions-against-russia-n54511)
This is something of a shrewd move. If we accept the fact that the Russian government is basically an organized cabal of kleptocrats with delusions of empire and a nuclear first-strike capability, why not bring some economic pain that might make some of the pirates turn on some of the others? Putin's power comes basically from being the first among thieves. That's how he maintains control over, among other things, the military. If some of his cronies hear their bank accounts scream, there's no telling what the consequences will be. . . One has to presume that these sanctions are the first step in ratcheting up pressure. Besides, they're what's left. There's something to be said for keeping your options open when you don't have that many of them.