Ever since Russia invaded Crimea there has been a clamor in Washington to “do something” even though it has little strategic or economic import to America and we lack any real leverage over the situation. So faced with the pressure to “do something” President Obama technically did something today.
He announced new sanctions on 20 high-level Russians as well as a bank in Russia. The practical affect of this move will be very small. No one honestly thinks these sanctions will cause Putin to withdraw from Crimea.
The United States simply has no viable tools to significantly impact the situation in the short term. Military action would mean declaring war on Russia over this small piece of land which would be absurd. In addition, since Europe is the main purchaser of Russian gas they are the only ones that could actually impose crippling economic sanctions.
So we have done something minor that will not accomplish much so we can say we did something. That is at least preferable to doing something really big and stupid just to make the same point.