What I've heard is the Saudi's may have reason to be cautious about stating the attacks originated in Iran. The U.S. reported activity in Iran but not sure it was beyond normal activity? No missile launches were reported as far as I know? One would think if we detected missiles or drones headed to Saudi Arabia from Iran we would have contacted them or taken some action? According to the Saudi reports some of the parts in the missiles weren't believed to be Iranian and they have no conclusive evidence of the direction of attack. Which raise the question could the attack have originated from the sea or southern Iraq by either a proxy or secret Iranian force?
I present this idea since its not reported that Iran has been trying to establish Shiite religion into Sunni areas of Iraq and a two way road between Lebanon and Iran. Iraq has allowed Iran to transport troops and equipment through Iraq from Syria and some opposite but not military or heavy equipment. It was reported a few months ago that some of the troops and equipment which left Syria didn't cross into Iran. The rumors are the troops were Quds forces and the equipment was special. There are also rumors Hezbollah has moved forces into Iraq which are aiding the Shiite militias. Which raise the questions of how far have they moved into Iraq, how many and what is their purpose?.
I understand Sunni converts to Shiite are offered $200,a new ID card which allows them unrestricted movement and actions, free education and other benefits. The majority of conversions are supposedly along the Syrian Iraq border and the roadway from Syria to Iran. These converts would ensure Shiite control over the roadway.
Iran is challenging the balance of power in the ME and from certain vantage points is being successful.
So maybe the attack didn't originate in Iran?