Later this month, under conditions of extreme security, Barack Obama will jet into Baghdad for policy discussions with America’s most popular general that could change the course of US involvement in Iraq. The long-awaited meeting with General David Petraeus, commander of coalition forces in Iraq, is likely to prove the most dangerous encounter – politically and personally – of a week-long world tour that will carry the Democratic presidential candidate from high-profile meetings in London, Paris, Rome and Berlin to the military bases of Afghanistan and Iraq. The candidate and the general have for months seemed at loggerheads over troop levels in Iraq, with Obama committed to a rapid withdrawal over the next 18 months and Petraeus arguing that a premature pull-out might endanger the success of the US military “surge” that has produced a sharp drop in violence this year.