Ben Hubbard

The execution of Sheikh Nimr al-Nimr, an outspoken campaigner for Shiite rights, is likely to exacerbate sectarian tensions across the Middle East.

The Islamic State saw this crossroads as a prime place to expand its caliphate. It was far from the major interests of the Syrian government in Damascus and along good river and road networks to allow the quick movement of fighters and contraband.

During the 1980s and '90s, the historic alliance between the wealthy monarchy of Saudi Arabia and the country's powerful clerics emerged as the major financier of international jihad, channeling tens of millions of dollars to Muslim fighters in Afghanistan, Bosnia and elsewhere. Among the project's major patrons was Prince Salman bin Abdul-Aziz Al Saud Salman, who last month became Saudi Arabia's king.