For the first time since 2006, the Lebanese are again facing the prospect of a devastating war with Israel, on the back of the current conflict in Gaza. Much of the population does not want, and knows it cannot afford, such a war. Lebanon is still in the throes of an economic collapse that began in 2019. Yet Hezbollah, which dominates Lebanon’s political scene, seems moved less by what its countrymen want than by the strategic priorities of its sponsor, Iran.

The Iranians have worked painstakingly in the past decade to build up a redoubtable deterrence capability on Israel’s borders with Lebanon, Syria, and Gaza. Hezbollah realizes that a full-scale conflict might weaken its hold over Lebanon and will try to avoid such an outcome. But ultimately, the party will follow Iran’s lead.  

Earlier this year, Hezbollah’s secretary general, Hassan Nasrallah, began referring to a “unification of the fronts” strategy. The idea was that Iran-backed armed groups, joined into the so-called Axis of Resistance, would coordinate operations against Israel, especially in defense of Muslim holy sites in Jerusalem such as the Al-Aqsa Mosque. Last May, amid clashes in Gaza between Islamic Jihad and Israel, Nasrallah described what this meant in practical terms: “The real headline for the resistance response in Gaza is [the creation of] a joint operations room for the resistance groups.”

Collaborative planning and operations have been facilitated by the fact that leading Hamas officials have relocated to Lebanon in recent months, most of them regarded as representing the pro-Iran, pro-Hezbollah wing of the organization. Ziyad al-Nakhalah, the head of Islamic Jihad, which has long had close ties to Iran, is also based in the country. Although support for the Palestinian cause is at the heart of Iran’s and Hezbollah’s identity, many Lebanese, Shiites among them, remain wary. They recall with trepidation how their country suffered during the Palestinian armed presence from the late 1960s to the early ’80s, particularly when Israel’s retaliation against Palestinian attacks destroyed Shiite villages. That Hezbollah has not factored this into its calculations is surprising.

[Read: Is Israel at war with Iran?]

For Hezbollah, one reason for overlooking the domestic discontent may be that throughout the Middle East, Iran’s effort to increase its influence is succeeding. As far back as the early ’80s, Iran understood that if it empowered and backed cohesive armed groups in fragmented societies, especially Shiite groups, it could then push them into the commanding heights of states even where Shiites were not a majority. Hezbollah was the most successful example of this model, but Iran also replicated it in Iraq in the decade after the 2003 U.S. invasion; in Yemen, where it has supported the Houthis; and in Syria, where it backs the Alawite-dominated regime of President Bashar al-Assad.  

The Iranian strategy is not entirely sectarian so much as it is linked to a revolutionary vision of Islam and an ideology of “resistance” directed against the United States, Israel, and conservative Arab countries in the region. From the start, the Iranians sought to build relationships with Sunni Islamist groups, such as Hamas and Islamic Jihad. As the French scholar Bernard Rougier wrote in his book Everyday Jihad, Iran’s ambassador in Beirut helped bring radical Sunni Lebanese and Palestinian clerics together to create the Association of Muslim Scholars in early 1982.

What took place on October 7 was part of a broader effort by the Axis of Resistance to expand its sway over the Palestinian cause. The Biden administration has said it’s seen no evidence of Iranian involvement in the Hamas attack, but the point may be a semantic one. Hamas’s leadership in Gaza, including Yahya Sinwar, as well as the organization’s senior official in Beirut, Saleh al-Arouri, are close to Hezbollah, as is the Islamic Jihad’s al-Nakhalah. Even if the Hamas operation was tightly compartmentalized, Hezbollah must have been aware of aspects of the plan, which means the Iranians were too.

In the past two decades, Iran has taken advantage of U.S. missteps in the Middle East. The U.S. invasion of Iraq eliminated Sunni dominance in the country, allowing Shiite parties with ties to Tehran to seize power. Successive administrations, starting with Barack Obama’s, disengaged from the region. As Obama told The Atlantic in a 2016 interview, “The competition between the Saudis and the Iranians—which has helped to feed proxy wars and chaos in Syria and Iraq and Yemen—requires us to say to our friends as well as to the Iranians that they need to find an effective way to share the neighborhood and institute some sort of cold peace.” As he saw it, the ensuing equilibrium would allow the United States to refocus on regions more vital to its interests.  

Obama’s words must have been music to Iranian ears—a U.S. president acknowledging Tehran’s stakes in the Middle East while downgrading the U.S. role there. The Iranians took advantage of American disengagement to develop their regional alliances. At the head of this effort was Qassem Soleimani, the leader of the Quds Force of Iran’s Islamic Revolutionary Guard Corps, whom the United States assassinated in January 2020. In Iraq, he cemented ties with militias in the Popular Mobilization Forces, formed in 2014 to fight the Islamic State. Last week, a leading PMF militia, Kataeb Hezbollah, whose leader was assassinated alongside Soleimani, announced that it had joined Hamas’s “Al-Aqsa Flood” operation against Israel and would increase efforts to target the United States.     

Similarly, the conflict in Yemen, which began in 2014, allowed the Iranians to develop relations with Ansar Allah, better known as the Houthis, whom they supported in order to put pressure on Saudi Arabia and other Gulf states. The Houthis are not, strictly speaking, an Iranian proxy force, but they are a part of Iran’s regional network of militias and have close ties with Hezbollah. The Houthis launched cruise missiles and drones either at Israel or at U.S. ships in the Red Sea last week, demonstrating that they are part of the coalition of forces Iran can call on if the Gaza war spreads.

[Read: Hezbollah watches and waits]

In Syria, the Iranians also retain the option to strike Israel from across the Golan Heights. Kheder Khaddour, a scholar of Syria at the Carnegie Middle East Center, told me, “Iran is redeploying [pro-Iranian] militias from northern Syria, including Aleppo, to the country’s south” for a possible conflict there. Israel has bombed the Damascus and Aleppo airports, almost certainly because it anticipates that Iran will open a Golan front in a wider war and use the airports to ferry in weapons.

The Axis of Resistance has shown that Israel is vulnerable—and that if Washington can be made to fear becoming embroiled in a regional war, it will press Israel not to attack Axis members. A week after the October 7 operation, the Israeli journalist Barak Ravid revealed that Iran had warned Israel that, although it did not seek a regional conflict, any land invasion of Gaza would bring about an Iranian intervention. The Biden administration is conducting back-channel talks with Iran, suggesting that the message reached Washington too.

The Americans surely want to avoid another Middle Eastern war in the run-up to the presidential election next year. President Joe Biden’s visit to Israel was partly an effort to hold back the Israelis. He warned them to be “deliberate” and to ask “very hard questions” about whether the path they were on would lead to their desired objectives. Hamas’s release of two American hostages and two Israelis seems to indicate that a broader arrangement may be in the works. But the real message of the past two weeks is that Iran has an extensive network in place to back up its challenge to U.S. priorities in the Middle East.