The new year is off to a decidedly ominous start in an increasingly ominous region as Saudi Arabia’s execution of a popular Shiite cleric caused an uproar in Iran. The two countries have severed diplomatic ties as other leaders in the region begin to choose sides. From WaPo: “The rupture sets the region’s two biggest powerhouses on a collision course at a critical time for U.S.-led diplomacy in the Middle East, and it raised the specter of worsening violence in the countries where they back rival factions, such as Iraq, Yemen and Syria.”

+ BBC: Relations between Saudi Arabia and Iran are at their worst for nearly 30 years.

+ WSJ: Who was Shiite cleric Nemer al-Nemer?

+ NYT: How Do Sunni and Shia Islam Differ?