Then-Vice President Joe Biden was right when he urged then-President Barack Obama to withdraw troops from Afghanistan, the former Chairman of the Joint Chiefs of Staff Adm. Mike Mullen said Sunday, adding that the US could have left Afghanistan earlier. "I thought we could turn it around, obviously, I was wrong," Mullen, who served in both Democratic and Republican administrations, told ABC News on "This Week." Mullen also said that the US should have withdrawn its troops after the killing of al Qaeda leader Osama bin Laden in 2011. "I think in retrospect, yeah we should have (left) ... I...