The United States is spending more money than ever on private security contractors in Iraq. This year, spending on mercenaries, who protect diplomats, civilian facilities and supply convoys, is projected to exceed $1.2 billion, according to federal contract and budget data obtained by USA TODAY. Most of that bill -- about $1 billion -- is State Department spending, which is up 13% over 2007. The remaining $200 million covers Pentagon contracts. Congress is raising concerns about the costs of relying on contractors for that work and the challenges of ensuring that they are supervised properly.