Washington was at war with Sunni jihadis for two decades during the global war on terrorism. Now, with both the United States and Israel embroiled in a major conflict with Iran, the end of the Islamic regime could be in sight.

If it does collapse, the result could be a tidal wave of Shiite extremism unleashed across the globe.

Washington was at war with Sunni jihadis for two decades during the global war on terrorism. Now, with both the United States and Israel embroiled in a major conflict with Iran, the end of the Islamic regime could be in sight.

If it does collapse, the result could be a tidal wave of Shiite extremism unleashed across the globe.

In late February, an Israeli strike killed Iran’s supreme leader, Ayatollah Ali Khamenei, one of the most important leaders in Shiite Islam and the embodiment of the Islamic Revolution’s velayat-e faqih system, blending religious and political authority. His targeted assassination risks catalyzing a cadre of militants across the Middle East. Hezbollah in Lebanon has already entered the fray, and both Iraqi Shiite militias and the Houthis in Yemen are likely to do so next, depending on the progression of Israeli-U.S. strikes and the defense posture of Iran.

The United States and Israel will continue to pound Iran and its Islamic Revolutionary Guard Corps (IRGC), eliminating leadership in the military, intelligence, and security services—at least until there is a diplomatic off-ramp. As each IRGC unit is eliminated, it will severely degrade command and control over the proxy groups in the region. Perhaps counterintuitively, this could make them more dangerous and unpredictable. Iran’s mosaic defense strategy aligns with an already decentralized approach. But further attrition could lead Iranian proxies to focus more on their own priorities, which could begin to further diverge from Tehran’s.

If groups splinter, this could usher in a new threat landscape, defined by terrorist tactics without a broader coherent strategy. And if Shiite extremist groups do fracture, it could lead to a surge in attacks by these organizations, as groups that were once hierarchically structured become decentralized and resort to their comparative advantage: terrorism.

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Hezbollah and other proxies will be determined to stay in the fight. The current war is their modern-day Battle of Karbala, in which in 680 C.E. the third Shiite Imam Husayn ibn Ali, the grandson of the Prophet Mohammed, was killed alongside a small group of supporters by the forces of the Umayyad Caliph Yazid I, whose rule Husayn deemed unjust and illegitimate. For these Shiite groups, their actions are steeped in reverence for martyrdom, and rather than run and hide, the most hardcore elements will seek to fight and die with honor.

A rump IRGC and proxies in various states of disarray could manifest in attacks against U.S. or Jewish targets across the globe. Attacks could look similar to Hezbollah’s in the early 1990s in Argentina, at Khobar Towers in Saudi Arabia in 1996, or in Bulgaria in 2012. Iranian proxies could seek to emulate what al Qaeda did with the 1998 East Africa embassy bombings or conduct attacks against hotels, tourist sites, and soft targets across the globe.

As part of Iran’s defense and foreign-policy strategy, Tehran spent years building, training, and equipping Shiite militias across the Middle East. During the Syrian civil war, which kicked off in 2011, Iran recruited roughly 50,000 Afghan and Pakistani Shiite fighters, who entered the battlefield as the Fatemiyoun and Zainabiyoun brigades. While these brigades proved critically important to Iran’s strategy during the Syrian civil war, they remained important to Tehran’s regional plan after. In fact, many of Iran’s regional proxies, from Fatemiyoun to Kataib Hezbollah in Iraq, have been deployed over the years by the Iranian regime to quell domestic unrest, including in the January uprisings.

In a scenario without Iran’s Quds Force directing these groups, they will need to find a new direction, and they may very well find it through conducting acts of terrorism against the new regional architecture that emerges following the end of this current war. One possible, if not likely, scenario for Iran is a state where IRGC hard-liners and their supporters control pockets of territory throughout the region, battling other groups, all vying for power.

After decapitation strikes on hierarchically organized militant organizations, internal power struggles often follow. After the United States assassinated Quds Force leader Qassem Suleimani in Baghdad in 2020—alongside Abu Mahdi al-Muhandis, the operational commander of the Popular Mobilization Forces—Iraq’s Shiite militias jockeyed for control and resources within the existing power structure that had once kept them in line. These groups could also begin competing with one another and, as the theory of outbidding proposes, engage in extreme acts of violence to prove to supporters and would-be recruits that their group is on top. This would be distinct from the previously seen competition among groups, which, according to Shiite militia expert Phillip Smyth, was a deliberate strategy crafted by Iran to keep them under its control.

To grapple with such a scenario, it is important to consider the pull and push factors of the rise of Sunni jihadism and overlay them with the modus operandi of Iran’s proxies. The single-most powerful driver across every Sunni jihadi wave over the past four decades has been the “push factor” of foreign occupation and the perceived humiliation of having foreign troops in Muslim lands: from the Soviet invasion of Afghanistan in 1979 to the de facto permanent stationing of U.S. troops in Saudi Arabia after 1991 to the 2003 U.S. invasion of Iraq. All of these events were a recruitment boon for al Qaeda and a host of other Salafi jihadi groups.

Operation Epic Fury is arguably more provocative than some of these operations and hits the same pain point of perceived foreign imperialism, with the minutiae broadcast live. The grievance here is concrete, and material to substantiate it is abundant: A joint U.S.-Israeli operation has killed the faqih, and footage of Khamenei’s compound in ruins has circulated widely. There are other flashpoints, too—girls massacred at an elementary school in Minab have become symbolic of the indiscriminate nature of targeting, as has rain mixed with oil showering Tehran after an Israeli strike on oil depots.

War also makes for strange bedfellows. During the de-Baathification campaign in Iraq in 2003, many Sunni military officers were targeted simply for their sect. Accordingly, joining or at least working closely with groups such as al Qaeda in Iraq became more appealing for the secular Baathists. A similar dynamic occurred in Syria, where the Assads’ Alawite-dominated security state brutalized the Sunni majority for decades, leading to the establishment of terrorist groups in the country. Perceptions of Shiite marginalization across the region, or any retaliatory strikes by the Sunni-majority Gulf states on Iran, may create a similar fertile ground for Shiite extremist recruitment.

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The most important “pull factors” for Salafi jihadi recruitment included a compelling universal ideology, charismatic leadership, financial incentives, and a sense of belonging. The foundational ideas of Salafi jihadism made individual acts of terrorism and participation in local conflicts part of a much larger, universal project. Even highly localized Sunni groups shared an ideological architecture—rooted in the writings of Sayyid Qutb and the jihadi theorists that came after him—that made their acts of violence part of a single, borderless struggle. This is fundamentally different from Shiite theology, which has had a more challenging time connecting various groups throughout the region, even when under Iran’s so-called Axis of Resistance umbrella. As U.S. Army Col. Thomas F. Lynch III argued in 2008, the patterns of Shiite terrorism are driven less by a unifying doctrine and more so by the political objectives of the Iranian state.

The Axis of Resistance and Iran’s goal to “export” the Islamic Revolution seek to compensate for the absence of the theological glue that binds Sunni groups together. With Iran’s role as a centrifugal force in doubt, terrorism patterns could mimic those of Salafi jihadis.

Further exacerbating the global pull of Salafi jihadism was the propaganda machine that was able to radiate out the messages of these charismatic figures globally—an art perfected by the Islamic State through its vast multilingual and graphically satisfying publications. While not as globally integrated as the Islamic State’s or al Qaeda’s propaganda systems, Shiite groups have maintained their own important propaganda channels, even if these are more regionally focused. Kataib Hezbollah’s recent propaganda campaign sought to engage in mass recruitment for suicide bombing attacks against U.S. targets if Washington and Tehran went to war.

Another pull factor in the Salafi jihadi movement has been financial incentives, from payments to fighters to promises of assistance to family members killed in action. Salafi jihadi groups are decentralized, and their funding is not state-sponsored. Iran’s proxies, meanwhile, have relied on a state-sponsored funding pipeline. Hezbollah’s annual budget from Iran has been estimated at hundreds of millions of dollars. The Houthis are also dependent on Iranian weapons shipments. In 2025, during U.S. operations against the Houthis in response to the group’s Red Sea attacks, the militants appealed to Iran for funding as they faced a financial crisis. This does not negate the importance of the criminal enterprises that Iran’s proxies have established to replenish their war chests, but it does indicate that these activities are no substitute for Iranian support. A loss in financing may actually encourage terrorist tactics, many of which can require limited funds.

Myriad variables could contribute to a growing wave of Shiite extremism across the Middle East. Revenge, fragmentation, and a desire to demonstrate relevance will all factor into what comes next. The United States and its Gulf allies are unprepared for what could come next.