It's been two years since the Americans trying to pursue Saudis in general and the Arab world in particular in accepting that Iran is not Arab, remember, that Arabs have strong bond to their clan system and according to them their first identity is from clan, the Arabs comes later and Moslem in the end.
After the end of the 1991 Gulf War which shook the whole Arab world, the Americans achieved multiple targets - First ofcourse was the fact for the Arabs that a superpower is lying next to your land, secondly the US invasion and subsequent battle with Saddam's army sort of laid a claim that "we saved your behind from Saddam's gigantic power". The Third one was the collective orders of US weapons came to a staggering figure of $ 38.8 Billion, which was necessary for ailing US arms industry.
The fourth one in the most sensitive issue, Saudi Arabia is the center of Sunni Islam, while Iran is the center of Shi'a Islam, the existence of these two in Iraq also fuels the situation wherein the Iraqui Shias looks towards Iran for support and the Sunnis to Saudi Arabia.
The US is playing the same game the British colonialists played in Arabia in the days of Ottoman Empire where they "nurtured" the growth of "Arab Nationalism" which at its peak was then used against Turks, whcih eventually caused the downfall of Ottoman Empire.
So, keeping these above said facts, I leave it on you to do the calculation but let me say that
"America is a like a big dog in a tiny room, every time it wages its tails, something falls off"