

In cash, but it was always risky. Couriers get intercepted, etc.
That said, I don’t think BTC is the best for CIA. It’s publicly traceable and that’s always been known. Of course if they have untraceable bank accounts and used those to buy the BTC, then it’s not particularly relevant. The spies can use their own tactics to hide their income.
Do people… go back to the tabs they leave open?