If, after the Islamic State (IS) claimed responsibility for the May 22 suicide bombing at a Shia mosque in Saudi Arabia’s Qatif region, you pointed out that this was neither their first attack nor was it likely to be their last, you would have been right. On May 29, Wilayat Nejd (Nejd is a name that refers to central Saudi Arabia) claimed another suicide attack in front of another Shia mosque—the al-Anoud Mosque—in Dammam. Four were killed. These two incidents, both during Friday prayers precisely one week apart, represent the most sophisticated attacks thus far, with the Qatif bombing by far the most deadly. When taken in the context of previous attacks, arrests and threats that can be traced back to the fall of 2014, they also represent a significant escalation.

The “Who”

The fact that Saudi nationals constitute the majority of militancy-related arrests and perpetrators of domestic militant attacks demonstrates that the country’s main threat stems from radicalized locals. Fighting between Saudi forces and Houthis along the southern border has remained localized to this area, while there have been only three attacks from abroad since July 2014 (two at or near the northern Arar border crossing with Arar and one at the southern Wadia border crossing with Yemen).

However, when it comes to radicalization, the twenty-six arrested members of the “terrorist cell” tied to the Qatif bombing and the bomber himself were all Saudi citizens. Similarly, the majority of the ninety-three arrested in April were Saudis, while the two connected to the April 8 Islamic State–linked shooting of two police officers in Riyadh were also Saudi citizens. In December, of 135 announced arrests, 109 were Saudi nationals. The three individuals tied to IS who were arrested in connection to the November 20 shooting of a Danish national were Saudis, and seventy-three of seventy-seven arrested for involvement in the November 3 shooting of Shia were citizens, to name a few examples.

While it has been argued that the Qatif bombing, and IS strategy overall in Saudi Arabia, may represent “lone-wolf” attacks, the opposite appears to be true. In addition to the claims of responsibility, the Ministry of Interior stated that the Qatif bomber “was wanted for being active member of an ISIS-affiliated terror cell since one year ago with 26 of its members, all Saudis, arrested so far.” The April arrests also included cells that were dismantled; one in Qassim reportedly had sixty-five members. The militant Sunni organization clearly has inspired more than lone-wolf attackers in this country.

The “What”

Within this time frame—that is, from September 2014 to now—there have been eight reported attacks, including the two most recent bombings and one whose motive remains unconfirmed (a January 2015 shooting incident that targeted two U.S. nationals working for a defense contractor). There were also various foiled plots and warnings issued by the U.S. Embassy. Among these incidents, there is a clear line of escalation—until the Qatif and Dammam bombings, they only involved shootings by individuals linked to IS. With the April arrests, more sophisticated, albeit foiled, bombing plots were revealed, such as the planned suicide car bomb against the U.S. Embassy. This has now culminated in successful suicide bombings and “official” claims by “Wilayat Nejd.”

These eight attacks, foiled plots and embassy warnings also reveal three clear and entirely unsurprising groups of targets that easily fit with IS’ modus operandi: Westerners, Shia and security personnel. In a November 2014 speech accepting oaths of allegiance from various groups, including one purportedly operating in Saudi Arabia, IS leader Abu Bakr al-Baghdadi specifically called for attacks against Shia, the Saudi royal family “and their soldiers before the Crusaders [Western nations] and their bases.”

The two recent targets, however, demonstrate a preference for Shia as the main target. As opposed to the Qatif region, there are multiple other potential targets in and around the city of Dammam. Yet, a Shia mosque was again attacked.

The “Why”

There are a few possible explanations. The more “desirable” targets, such as Western compounds, oil installations or government buildings, may have too much security for a successful attack. The group may also be interested in reducing the number of Sunni casualties. Although it can be argued that this was not a consideration of the group’s “Wilayat Sanaa” when it targeted mosques in the Yemeni capital that are attended by both Sunni and Shia, IS may be especially sensitive to the attitudes of the Saudi population. The country is likely deemed particularly important, given the presence of Mecca and Medina, and with already existing opposition to these bombings, the killing of Sunnis is probably not going to win many supporters. Meanwhile, attacking Shia may be the group’s overall aim: Stoke sectarian tensions enough in a country with an already frustrated Shia minority, and this minority might explode on its own.

So what now? The ideology of IS members and supporters is not likely to see arrests as a deterrent. With the Qatif and Dammam bombings clearly demonstrating that those detained in April and post-Qatif were not “everyone,” the unfortunate reality is that more attempted and successful attacks should be expected. The Saudi leadership has a reason to be very concerned, and not only because attacks in Dammam are frightening, especially to the many foreigners operating in the oil-rich Eastern Province (the United States has a consulate a stone’s throw away in Dhahran). The Shia population has long had grievances with the government, and while some reform was implemented, it has been slow, limited and largely seen as insufficient.

Already, there is a distinct possibility that, in the long term, unrest will slowly increase in the absence of concrete change. With some Saudi Sunni clerics themselves expressing intolerance toward Shia, the arrest of perpetrators and the Crown Prince’s visits to the victims are likely to be deemed inadequate responses to these bombings and any more that may occur. Failing to take this opportunity to institute reform—even if gradual—vis-à-vis the Shia population may see the government inadvertently assisting any IS aim to further foment sectarian unrest. The leadership may be focused on Yemen, but that doesn’t mean they can’t walk and chew gum at the same time.

Miriam Goldman is a Tel Aviv-based political and security analyst specializing in Gulf affairs. You can follow her on Twitter at @Miriam411.

Image: Wikimedia/United States Army Alaska