Amazingly, it appears that the risk of contract fraud, waste and abuse doesn't exist overseas, only here in the United States. At least according to Office of Management and Budget, and the White House.
A story in the Washington Post notes that a new rule that requires U.S. contractors to report fraud, waste and abuse (FW&A) they find while performing work provided an exemption to those contractors doing work overseas.
So, the only conclusion one can reach is that OMB doesn't think there is any risk of FW&A in overseas contracts, or that it is perfectly OK for U.S. contractors to ignore (or engage in?) FW&A overseas.