Sunni's and Shi'a hate each other, and have for centuries. Each believes that they are the true followers of Islam while the other is barely a step above the infidels. The Saudi's aren't only worried about nukes getting lobed over their heads... they are worried about nukes getting lobed on them as well.
Shi'as and Sunnis in Islam are like the Catholics and the Protestants. In some areas, they get along and in other areas they kill each other. Though their split involves the murder of one of Muhammad's grandsons, not just the nailing of theses to a door. Still, I'd submit that the average Saudi cleric or Iranian Ayatollah probably hates Israel more their counterpart across the Persian/Arabian Gulf. Though it may be a near thing.
We've never been prepared properly for war. The first Gulf War being the one possible exception. Rumsfeld did his level best to dork away OIF/OEF. Vietnam is self-explanatory. We couldn't end Korea. We tried like hell to stay out of WWI and WWII. The Civil War and Spanish-American wars had to have the Army ballooned by volunteers and/or draftees. We almost lost the War of 1812.
Heck, Washington was a fog-assisted retreat away from losing the Revolution in 1776.
The Turkey thing worries me. I wonder if Europe realizes they may have another war brewing on their doorstep just like they did 15-20 years ago.