Given the rulers that we and the USA have about corruption whilst conducting business transactions, I'm surprised that either country can legally sell them arms. In the early 90's I worked for a company that sold simulation systems for air combat to Saudi Arabia amongst other customers. Somebody told me that, just to get goods into the country you would have to pay a back hander to the customs agent or your goods would sit in a warehouse at the port forever waiting for clearance. All the bribes and corruption were documented at our end so they could be accounted for. Nowadays that sort of thing is surely illegal.
Saudi Arabia is corrupt from top to bottom. Its rulers do not care about its citizens because they make their money from oil rather than their people making stuff. It's a brutal regime and I do not understand how anybody could have the stomach to do business with them.
