Defense Secretary Robert Gates urged Iraq to host U.S. troops beyond the end of the year to maintain stability and keep Iran at bay, echoing the growing concerns of U.S. military officials that the government in Baghdad isn't moving fast enough to request an extension of the U.S. troop presence.

Mr. Gates predicted the U.S. would accede to such a request to send a message to American allies and Iran that the U.S. isn't withdrawing from the region, he said in remarks to a think tank in Washington on Tuesday.

"It...