Who Done it?
Well ???
The current Saudi leader is Regent Crown Prince Abdullah. Abdulla has been attempting to reform a religion that is, by its own internal laws, un-reformable. That has caused problems across the Muslim world because the leader of Saudi Arabi has the leadership of, at least the Sunni branch. Abdulla is trying to create a city where the Islamic rules will not be enforced so as to bring in foreign investment. It has, apparently, failed. Among other problems, it is on the Red Sea and requires significant cooperation with Israel. Which is another problem as for at least seventy years there has been propaganda against Israel.
I mention all of this so I can say, it’s entirely possible that the drones are bought and sent by some local Saudi dissident group.
If Abdulla fails, then Saudi Arabia is in serious trouble. A huge percentage of their GDP is based on oil. If/when the oil runs out or is not in such high demand then Saudi Arabia will need the industry it can only get through foreign investment. Entrepreneurial effort is not highly represented in Saudi culture.