Saudi authorities have reported uncovering a large jihadist network working for the Islamic State (IS). The group was responsible for at least one sectarian attack on Saudi Shiites. At the same time, the kingdom is frustrated that the West is cooperating with Iran to fight IS in Iraq in an "unholy alliance" that Riyadh fears will ease Tehran's isolation.

The Saudi Interior Ministry reported Nov. 24 that three Saudi citizens and a Qatari linked to IS had carried out an attack on a Shiite village in the oil-rich Eastern province in early November. The attack killed nine Shiites and injured 13. The jihadist cell was tracked and all four members killed or arrested. At least two Saudi police officers died in the clashes involving multiple gunfights. Another 77 suspects with alleged links to the killers — including a Jordanian, a Turk and a Syrian — were arrested. The rest are Saudis. The Interior Ministry does not often defend Shiites' rights, but in this case, it had no choice given the IS connection.

The network had pledged loyalty to IS leader Abu Bakr al-Baghdadi and took its orders from IS in Iraq and Syria, communicating frequently. IS chose the target and timing for the operation in the Eastern province. The attack took place at a Shiite mosque on the holy day of Ashoura, the anniversary of the martyrdom of Muhammad's grandson Hussein. Baghdadi clearly wants to expand his war on the Shiites to the Saudi kingdom and probably other Gulf states as well. Bahrain is another likely target.

The Saudis have been fighting al-Qaeda cells for more than a decade, but this is the first threat from IS. This week, Saudi courts convicted three members of al-Qaeda in the Arabian Peninsula for conspiracy to attack Interior Ministry headquarters in Riyadh.