Less than three years ago, references to an Iranian land bridge were infrequent. Moreover, they did not refer to the same routes under discussion today. Before the autumn of 2016, it seemed implausible that Iran could establish control of a corridor from Tehran to the Mediterranean. By 2017, however, assessments evolved rapidly in response to developments on Syrian and Iraqi battlefields. By early 2018, there was a rough consensus on the meaning of “land bridge,” although its significance is disputed.

The Islamic Republic has had designs on the Middle East since its inception in 1979. Exchanging the pro-American orientation and nationalism of its predecessor for pan-Islamist, anti-Western, and anti-Zionist ideals, the new Iranian government sought to export its revolution, hoping to undermine U.S.-aligned governments in the Middle East. In the early 1980s, Iran saw an opportunity to confront Israel and support the cause of Lebanese Shiites. The regime deployed several thousand members of the newly formed Islamic Revolutionary Guard Corps (IRGC) to the Bekaa Valley to begin training Lebanese fighters that would become Hezbollah. Iran also forged close ties with the Assad regime in Syria, whose proximity to Lebanon made it a critical source of support for the Lebanese group. Both the IRGC expedition to Lebanon and Iran’s drive to overthrow its Ba’athist adversary during the Iran-Iraq War (1980-1988), are early examples of Iran’s efforts to export its revolution.

With good reason, analysts today describe Lebanese Hezbollah as “the most successful, and the most deadly, export of the 1979 Iranian revolution.” Emboldened by revolutionary ideology but also cognizant of its own conventional military shortcomings, Tehran’s regional security strategy came to rely on a constellation of non-state actors like Hezbollah. Iran’s cultivation, arming, financing, and training of such forces enabled the regime to advance the cause of Iranian hegemony at a comparably low cost, while limiting the prospects for escalation or direct retaliation against Iran, since its role was indirect.

The U.S. invasion of Iraq in 2003 removed Saddam Hussein from power and opened the door to a long-term Iranian effort to co-opt the government of Iraq. Nonetheless, establishing control of a land corridor across Iraq remained out of the question because of the Sunni insurgency that raged in western Iraq along the Syrian border. The insurgency subsided in 2007-2008, but the continuing U.S. military presence posed a similar challenge. The U.S. began to draw down its forces in 2009, but in 2011, the Assad regime lost control of eastern Syria to Sunni rebel forces, thereby threatening Iran’s regional designs.

The outbreak of war in Syria sparked discussions in Washington about an Iranian land bridge, yet the phrase initially had a different meaning. Instead of a corridor from Tehran to the Mediterranean, the term described a set of shorter routes from Syrian airports and seaports to regions in Lebanon under Hezbollah control. In 2012, Washington Post editor Jackson Diehl observed, “The Syrian regime of Bashar al-Assad is Iran’s closest ally, and its link to the Arab Middle East. Syria has provided the land bridge for the transport of Iranian weapons and militants to Lebanon and the Gaza Strip.” “Without Syria,” he added, “Iran’s pretensions to regional hegemony, and its ability to challenge Israel, would be crippled.”

In 2013, Matthew Levitt, an expert on Hezbollah, said it was imperative for Assad to “maintain a land bridge for the resupply of Iranian weapons” to the Lebanese group by preserving control of Syria’s Mediterranean coastline. Shipments that arrived in the ports of Tartus, Baniyas, and Latakia could then move directly southward into Lebanon. Although cargo vessels are more cost effective than aircraft and have far greater capacity, they are also far more susceptible to interdiction. Thus, Assad became increasingly dependent on shipments via air, which began in early 2012, when Iraq first opened its airspace to Syria-bound flights from Iran. Iraq suspended the flights shortly after an April phone call from President Obama to Prime Minister Nouri al-Maliki, yet the flights resumed several months later. In effect, Iran was employing an air bridge to send manpower and weapons to Syria, some of which would move by land into Lebanon.

The Land Bridge Evolves

Iran’s growing influence in Iraq, thanks to the rise of the Popular Mobilization Forces (PMFs), spurred a redefinition of the land bridge as a corridor from Tehran to the Mediterranean, not just Damascus to Lebanon. While the PMFs are neither exclusively Shiite nor uniformly pro-Iran, they served as a vehicle for Iranian proxies such as Kataib Hezbollah, Asaib Ahl al-Haq, and others to expand their influence. In late 2015, Ali Khedery, formerly a top adviser to several U.S. ambassadors in Iraq, warned, “Iran may play a spoiler role and seek to preserve its ability to attack Israel by securing its land bridge across Iraq, Syria, and Lebanon.”

The first thorough assessments of the extended land bridge to the Mediterranean appeared in the fall of 2016, beginning with a Wall Street Journal story about Sunni Arabs’ fear that the fall of the Islamic State would be followed by “a potentially more dangerous challenge: a land corridor for Tehran to Beirut” under Iranian control. In October, the UK’s Guardian published the first detailed map of the alleged route, which crossed from Iran into central Iraq, then swung to the northwest, passing through the town of Sinjar, before entering Syria at the Rabia border crossing.

The accompanying story presented the emerging bridge as an “historic achievement more than three decades in the making.” According to correspondent Martin Chulov, the land corridor was one of Tehran’s “most coveted projects – securing an arc of influence across Iraq and Syria that would end at the Mediterranean Sea.” Drawing on anonymous sources he identified only as “regional officials,” Chulov asserted that Iran had a specific and well-established plan for building the land bridge, “coordinated by senior government and security officials in Tehran, Baghdad, and Damascus,” all under the guidance of IRGC Quds-Force (IRGC-QF) commander, Major General Qassem Soleimani.

Other Western observers agreed that a northerly route was the most plausible. As part of their drive toward Mosul, PMF units loyal to Tehran increased their presence in northwest Iraq. Following the PMF units’ capture of the airport in Tal Afar, a key city on the road from Mosul to Sinjar, analyst Hanin Ghaddar warned, “Iran May Be Using Iraq and Syria as a Bridge to Lebanon.” She noted, “If Iran succeeds, the three countries caught in the midst of this strategy could lose whatever is left of their sovereignty.”

The Southern Route Emerges

Ideas about the land bridge continued to evolve along with developments on the battlefield. In 2017, an Iranian-led coalition that included Shiite foreign militias and Assad regime forces began moving eastward toward the Syrian border with Iraq, eventually reaching the border town of Albu Kamal in the Euphrates River valley. In May, Israeli journalist Ehud Yaari assessed that Iran was “building two land corridors to the Mediterranean.” The first was the northern corridor that crossed through Sinjar. The second route followed the Euphrates out of Baghdad, snaking through the desert to the west and north until it reached the border town of al-Qaim before crossing into Syria. In October, Iraqi government forces and PMF units took the Rabia border crossing, previously controlled by Iraqi Kurds, reinforcing concerns about the northern route.

As summer ended in 2017, government officials, journalists, and policy experts began to discuss the land bridge with greater frequency. The Associated Press and Reuters both ran stories examining the land bridge and the Shiite militias that operated along its path. A key indicator of sustained interest in the land bridge was the work of INSS, an Israeli government-sponsored think tank, which published two lengthy treatments of the subject. The first article specified in detail three potential routes for the land bridge. In addition to the northern route and the southern route along the Euphrates, it identified a second southern route coming out of Baghdad and running toward the intersection of the Iraqi, Syrian, and Jordanian borders. The second article emphasized the indispensable role of Iranian-backed Shiite militias in securing a land corridor.

Michael Pregent of the Hudson Institute has produced maps that illustrate the presence of these militias across most of Iraq. “Call it Iran’s land-bridge, a permissive environment, or a FastPass to Syria – whatever you want to call it – it exists,” he told Congress. The phrase “permissive environment” underscores that important sections of the land bridge consist of zones of political influence rather than stretches of road or strategic border crossings. Throughout much of Iraq, Iranian-backed militias can operate without interference from security forces under the prime minister’s control. Thus, when moving illicit cargos, the militias can choose whichever route is most suitable at the moment.

In the fall of 2017, the land bridge took center stage for the first time at a congressional hearing titled “Confronting the Full Range of Iranian Threats.” In his opening remarks, Rep. Ed Royce (R-CA), then chairman of the House Foreign Affairs Committee, said,

[It is] critical that we stop Iran from completing a “land bridge” from Iran to Iraq to Syria to Lebanon. This would be an unacceptable risk and, frankly, a strategic defeat. It is not just Israel’s security on the line. I feel that if Iran secures this transit route, it will mark the end of the decades-long U.S. effort to support an independent Lebanon. Jordan’s security, too, would be imperiled.

Israeli Prime Minister Benjamin Netanyahu began to express similar concerns. In June 2017, Netanyahu made a brief reference to the Iranian pursuit of a land bridge. He elaborated further during a March 2018 address in Washington, saying the bridge would trace a route from “Tehran to Tartus on the Mediterranean,” enabling Iran “to attack Israel from closer hand.”