The US Secretary of State has made an unannounced visit to Iraq following the deadliest attack in nearly a year.Hillary Clinton said she saw no sign that the country is sliding back into sectarian warfare, despite recent suicide bombings. She also pledged to keep supporting the Iraqi government as Washington prepares to withdraw all its trooops by the end of 2011. Clinton’s trip comes a day after two female suicide bombers blew themselves up outside a Shi’ite Muslim shrine in Baghdad, killing 60 people. It was the third major attack in two days, bringing the two-day death toll to at least 150. An end of year election is also raising tensions as political parties and armed groups jostle for dominance of the oil-producing nation.