Probably a mini Iran-Contra. Get approval for paying $40m to [SECRET] to carry out acts of pro-US terrorism. Steal the gold. Tip off the enemies of the group so they fail/are killed/arrested. Then report to your superior that the mission was a failure due to enemy action.
Or get approval for $5m, run operation for $2m and pocket the rest. Operation has provable, demonstratable effects, and the falsified payoffs are mixed in with the real ones. If people check up on you, you can point them to assets still on the books to confirm a payoff or funding for equipment. Rinse and repeat. Its just embezzlement, but in an environment where the assets are supposed to not be traceable. Rinse and repeat.