Pentagon chief warns of 'tough year' for Afghanistan

US Defense Secretary Jim Mattis warned of "another tough year" in Afghanistan as he arrived on an unannounced visit Monday, hours after his Afghan counterpart resigned over a deadly Taliban attack that triggered anger and left the embattled army in disarray. Paying his first visit to Afghanistan as Pentagon chief, Mattis met with President Ashraf Ghani and other officials and US military commanders. "We're under no illusions about the challenges associated with this mission," he said at a press conference in Kabul with General John Nicholson, US commander of NATO forces in Afghanistan.