Wilayat Najd — literally "Najd Province," a naming convention referring to the location of the active cell — claimed the attack. The group identified al-Hammadi as the director of internal security for the region of al-Quwayiyah. Wilayat Najd has become increasingly active in the region, having already claimed responsibility for the April 3 detonation of two explosive devices next to a police station in the al-Kharj area of Riyadh, which killed one person and damaged three police vehicles.
Wilayat Najd is a self-styled affiliate of the Islamic State in Saudi Arabia. The group first claimed responsibility for an attack in May 2015, when it bombed a Shiite mosque in al-Qudaih, near Qatif, killing 21 and injuring 100. A week after the mosque attack, the group claimed another bombing. In this one, a man dressed as a woman detonated a suicide device that killed four people near a Shiite mosque in Dammam. Wilayat Najd also claimed responsibility for a suicide bombing on June 26, 2015, this time targeting a Shiite mosque in Kuwait's capital, killing 25 people. All of these attacks demonstrate a clear intent to replicate a strategy we have already seen in Iraq, where denominational targets are assaulted in an attempt to ignite a sectarian conflict that can consume the region. As of now, these attempts have failed to achieve their desired result.
Saudi Arabia has long fought to maintain its internal security, which is why the growing operational tempo of attacks in the Sunni core — predominantly in and around Riyadh, an area commonly known as the Najd — is of such concern. Shiite militancy is a given in Saudi Arabia. Violence between security forces and Shiite militants in the eastern provinces is commonplace, mainly because of the concentrated Shiite population. So far, Saudi security forces have managed to protect critical oil infrastructure and keep violence at tolerable levels within these areas. And while Sunni militant violence is not necessarily new to Saudi Arabia, the evolution of the Islamic State and its self-declared caliphate serves to both reinvigorate and modify the patterns of violence associated with Sunni groups. At first, attacks were random and relatively simple, but as of last year Sunni militants had started not only to rebrand themselves but also to apply some level of strategy to their work.
Parallel to that strategy, the same Sunni militants have consistently attacked security forces in and around Riyadh, using a mix of small arms and suicide explosive devices. Security checkpoints are the most common targets, or security forces out on patrol, which provide simple targets of opportunity. The April 5 attack stands slightly apart in that it suggests militants were able to identify a specific individual, either through intelligence or observation of his routine, and kill him. If true, this demonstrates that Sunni militants are taking incremental steps to improve their lethality by developing a growing array of skill sets.
Though this trend continues to vex and alarm Saudi security forces, attacks are still happening at a low enough level to be manageable. For roughly a year and a half, Riyadh has shown that the kingdom is well aware of the rising Sunni militancy and is taking steps to mitigate it in the form of large-scale arrests after attacks, followed by many executions. But the effectiveness of these measures in the long run remains questionable. In one respect, they are undoubtedly disruptive to the militants and likely head off some attacks. Yet mass arrests also tend to alienate and disgruntle large portions of the population, working to the militants' advantage when it comes to recruitment and gaining cooperation from the people. Perhaps the biggest concern is that groups such as Wilayat Najd are persistent, despite the hard work underway to destroy them. And as the Islamic State core continues to lose territory elsewhere, more militants are returning home from the battlefront. These individuals bring with them massive amounts of practical combat experience, boosting militant groups' capabilities as well as their numbers.