What Should the US do About ISIS-If Anything?

Kill as many of those cockroaches as they can. Thats what 'should' be done.

What 'can' be done is the Arabs 'can' pound ISIS controlled targets again tonight with more air syrikes, keep that up for a week then switch off and the U.S. 'can' take the shift; eventually the Brits will join in- they are a little late to the game on this one but they 'can' and will get thier licks in.

The US by the US Presidents recent speech is already committed to destroying ISIS by force wherever it's found as part of the 40 nation collation to do so and with UN, EU, world community backing.

I suppose that I am not knowledgeable enough about the situation and its potential dangers to answer correctly.

I hope that the U.S. President is sufficiently knowledgeable or is being made sufficiently knowledgeable to make the most reasonable and effective decision. So far, Obama has not proved to be a failure in military matters (though the war in Afghanistan has continued far longer than expected).

I hope and pray that the people in charge will have enough knowledge and sense to make the decision that seems best. I do not have that knowledge, so it is pointless for me to second-guess those people.

The allies are doing what is necessary from the air - the advances have been halted and the Kurds are hitting them back on the ground

Fight them over their before they come over here. It is just a couple hours of flight for them to bring it over here.

We created this mess, so we need to fix it. Bomb them until they are no more.