All of this leads some to suspect that private contractors are being used for military operations that are either too controversial to sell to the public or that would otherwise be subject to congressional restrictions...Increasingly, peacekeeping and humanitarian operations depend on private military companies to provide basic services...Many governments view PMCs as challenging states' sovereignty and monopoly on legitimate violence. Lack of accountability is another objection. There are well-established procedures to deal with war crimes committed by serving soldiers; with PMCs, it is far less clear who should take responsibility when things go wrong...What legal liability do contractors have if they kill or injure civilians, intentionally or by accident? [article refers to DynCorp, Northrop Grumman, Lockheed-Martin, ARINC, ICI, Pacific Architects and Engineers, Executive Outcomes, MPRI, AirScan, Sandline International, Northbridge Services Group]