A rocket was fired into Baghdads fortified Green Zone but caused no casualties, the Iraqi military said on Sunday. "A Katyusha rocket fell in the middle of the Green Zone without causing any losses," the military said in a statement. Alert sirens sounded briefly in Baghdad after the explosion was heard, according to Associated Press reporters on the east side of the Tigris River. The Green Zone is home to government headquarters and the US Embassy. The attack comes amid heightened tensions across the Arabian Gulf, after the White House ordered warships and bombers to the region earlier this month to counter the Iranian threat. The US also has ordered nonessential staff out of its diplomatic posts in Iraq.