Fuchs rightly posted on a separate thread, with my emphasis:
The Americans never really mastered this indirect rule and the setup of effective indigenous sepoy-like forces either.
Yes such forces would appear to be mercenaries and history shows that money was one factor in a sometimes complex equation. If the British in the imperial period could raise irregular units in the NW Frontier Province and FATA, with very few examples of mutiny or disloyalty, can this not be replicated? More recently and in a non-imperial context there were local units in Borneo, Oman, Namibia etc.

Are there not American examples post-1945? i am sure there are pre-1939.