What Will U.S. Troops in Baghdad Do When Islamic State Militants Arrive?

There are several stories today about how Islamic State militants are threatening Baghdad.  Some of the stories suggest that “an all-out assault on Baghdad” may be in the cards, while others say that the militants will instead simply “wreak havoc” on the city from its western edge.  Whichever is right, Islamic State forces are threatening Baghdad itself.

President Obama has pledged that he will not put American boots on the ground in order to degrade and destroy the Islamic State.  But he has already sent 1000-1500 troops to Baghdad to provide (in the words of a June 30 letter to Congress) "support and security for U.S. personnel and the U.S. Embassy in Baghdad.”  And so quickly the question is becoming:  What will the U.S. boots on the ground in Baghdad do if and when the Islamic State brings the fight to them?