Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: How big of a threat is ISIS really? The White House wants to find out and is deploying as many as 300 military advisers to Iraq to assess the might of the Islamic State in Iraq and Syria. The jihadi group's rash battlefield successes make it look extremely fierce. ISIS militants have surged from the border with Syria to blitz major cities in Iraq's northern Sunni region, taking Tal Afar and Mosul, then moving quickly south. Hundreds of thousands of civilians fled from their path, creating a new refugee crisis. They have advanced on Baquba, just north of Baghdad, and are threatening to attack the capital.The White House wants advisers to assess the dangers ISIS posesThey will also support Iraqi troops by forming joint operation centersExperts are split on what they will actually do -- gather intel in offices or advise troops closelyThey also disagree on whether or not they should go at all 
 Question:When the ISIS jihadis overran the northern cities, many _ troops put up little resistance and fled.

Iraq