U.S. Defense Secretary Robert Gates met his top military commanders in Iraq on Monday to discuss the pace of U.S. troop reductions, a day after militants killed more than 50 people in a spate of attacks, according to Reuters. President George W. Bush ordered 30,000 extra troops to Iraq a year ago to curb rampant sectarian violence. U.S. troop numbers have begun to fall because of an overall improvement in security in the past few months and as more Iraqi troops and police are trained and deployed. There are about 155,000 U.S. troops in Iraq. Gates, who arrived in Baghdad late on Sunday, told reporters travelling with him that his talks on troop levels with the U.S. military commander in Iraq, General David Petraeus, would cover a "whole range of possibilities". By July, U.S. force levels will have dropped by five brigades, bringing numbers to roughly 130,000, or the same as before the additional deployments began in early 2007. Petraeus said in a CNN interview last month he would need some time to "let things settle a bit" after the initial reduction, prompting speculation he wanted to keep about 130,000 troops or more in Iraq well into the second half of the year. Only one of the five brigades has left Iraq so far, and Gates said he expected to hear about plans for removing the other four. He has said he hoped for reductions at the same pace in the second half of 2008.