U.S. Defense Secretary Ash Carter arrived on an unannounced visit to Baghdad on Saturday to get an assessment of the U.S.-backed Iraqi campaign to retake Mosul from Islamic State.
 
 

"We will see the prime minister (Haider al-Abadi) and get his best assessment on where we are with the Mosul operations," a senior U.S. defense official said, briefing reporters ahead of the trip.
 
 

"It's the beginning of the campaign. We do feel positively about how things have started off, particularly with the complicated nature of this operation."