Barack Obama, the US presidential candidate, has called the situation in Afghanistan "precarious and urgent". Obama, who visited US troops in Afghanistan and met Hamid Karzai, the Afghan president, said on Sunday the US should start planning immediately for a shift of soldiers from Iraq to Afghanistan. "I think the situation is getting urgent enough that we have to start doing something now," he told the US TV network CBS. Television pictures showed a relaxed Obama at the heavily guarded presidential palace in Kabul, talking to Karzai and flanked by Afghan ministers and fellow senators Chuck Hagel and Jack Reed....