President Barack Obama came out swinging Friday against congressional attempts to slap fresh sanctions on Iran, warning such a move would likely destroy nuclear talks and increase prospects for a military showdown. Vowing to veto any sanctions that reach his desk, Obama pleaded, “Just hold your fire.” In an unusual move by a foreign leader, British Prime Minister David Cameron said he was personally calling U.S. senators to say that new sanctions would drive a wedge through international unity. Standing side by side with Cameron at the White House, Obama said world powers would be sympathetic to Iran and would blame the U.S. if Congress moved ahead with more sanctions while fragile negotiations are under way. At that point, Obama argued, the world would lose its best chance to prevent Iran from obtaining a nuclear […]