AIKEN, S.C. - White House hopeful Barack Obama on Saturday said private security contractors in Iraq are raising the risk for U.S. troops because Iraqis don't distinguish between the forces. He also criticized the pay disparity between soldiers and private contractors. "You've got young men and women signing up to serve, willing to spill blood for America. How could they be treated less well than private contractors?" Obama told a crowd of more than 1,400 at a high school gymnasium in this early voting state. "And these private contractors, they go out and they're spraying bullets and hitting civilians and...