Hamed Wardak, the soft-spoken Georgetown University-educated son of an Afghan cabinet minister, has a Defense Department contract worth up to $360 million to transport U.S. military goods through some of the most insecure territory in Afghanistan. But his company has no trucks.

Instead, Wardak sits atop a murky pyramid of Afghan subcontractors who provide the vehicles and safeguard their passage. U.S. military officials say they are satisfied with the results, but they concede that they have little knowledge or control over where the money ends up.