CHL will have the best contact details. Establish if it is the US Govt on its own or if the contract is within ISAF (NATO), you may be able to make contact through NATO (see its website). Via ISAF, the US has a working relationship with 44 nations in Afghanistan, chances are that for a civilian support contract Swiss is fine. The DoD can be very pragmatic when it wants to be, currently employing ex-KLA insurgents in various 'secure' places (remember Kosovo?).