A senior U.S. military official said on Wednesday attacks by Iranian-backed groups on bases hosting U.S. forces in Iraq were gathering pace and becoming more sophisticated, pushing all sides closer to an uncontrollable escalation. His warning came two days after four Katyusha rockets struck a base near Baghdad international airport, wounding five members of Iraq’s elite Counter-Terrorism Service. It was the latest in a spate of rocket strikes in the past five weeks on military installations hosting members of the U.S.-led coalition whose objective is to defeat Islamic State insurgents. The official said the attacks were jeopardizing the coalition’s ability to combat Islamic State insurgents. The tension between the United States and Iran has ramped up in the region over U.S. economic sanctions that are hitting Tehran hard. The two sides have traded blame over attacks on oil installations, militia arms depots as well as military bases […]