Introduction

Hezbollah is a Shiite Muslim political party and militant group based in Lebanon, where it has fostered a reputation as “a state within a state.” Founded during the chaos of the fifteen-year Lebanese Civil War (1975–1990), the Iran-backed group is driven by its violent opposition to Israel and its resistance to Western influence in the Middle East.

Hezbollah is considered a terrorist organization by the United States and many other countries, and has deep-rooted military alliances with repressive, anti-Israel regimes in Iran and Syria. Cross-border clashes between Hezbollah and Israel escalated in recent years, particularly amid Israel’s ongoing war with Hamas in the Gaza Strip that broke out last year. In a major intensification of its battle with Hezbollah, in late 2024 Israel killed longtime leader Hassan Nasrallah, and launched a ground offensive against the group in southern Lebanon.

How did Hezbollah originate?

Hezbollah emerged during Lebanon’s civil war, which broke out in 1975 when long-simmering discontent over the large, armed Palestinian presence in the country reached a boiling point. Various Lebanese sectarian communities held different positions on the nature of the Palestinian challenge.

Under a 1943 political agreement, political power is divided among Lebanon’s predominant religious groups—a Sunni Muslim serves as prime minister, a Maronite Christian as president, and a Shiite Muslim as the speaker of Parliament. Tensions among these groups evolved into civil war as several factors upset the delicate balance. The Sunni population had grown with the arrival of Palestinian refugees in Lebanon, while Shiites felt increasingly marginalized by the ruling Christian minority. Amid the infighting, Israeli forces invaded southern Lebanon in 1978 and again in 1982 to expel Palestinian guerrilla fighters that used the region as their base to attack Israel.

A group of Shiites influenced by the theocratic government in Iran—the region’s major Shiite government, which came to power in 1979—took up arms against the Israeli occupation. Seeing an opportunity to expand its influence in Arab states, Iran and its Islamic Revolutionary Guard Corps (IRGC) provided funds and training to the budding militia, which adopted the name Hezbollah, meaning “The Party of God.” It earned a reputation for extremist militancy due to its frequent clashes with rival Shiite militias, such as the Amal Movement, and its attacks on foreign targets, including the 1983 suicide bombing of barracks housing U.S. and French troops in Beirut, in which more than three hundred people died. Hezbollah became a vital asset to Iran, bridging Shiite Arab-Persian divides as Tehran established proxies throughout the Middle East.

Hezbollah bills itself as a Shiite resistance movement, and it enshrined its ideology in a 1985 manifesto that vowed to expel Western powers from Lebanon, called for the destruction of the Israeli state, and pledged allegiance to Iran’s supreme leader. It also advocated an Iran-inspired Islamist regime, but emphasized that the Lebanese people should have the freedom of self-determination.

Who was Hezbollah’s leader, Hassan Nasrallah?

Hassan Nasrallah helped found Hezbollah in the early 1980s and led the group for more than thirty years, until he was killed by an Israeli air strike in September 2024. Many Middle East experts credit the Beirut-born Shia cleric with molding Hezbollah into the most formidable non-state fighting force in the region, and Iran’s most powerful anti-Israel proxy. 

“Among Nasrallah’s most important achievements was enmeshing Israel in an enervating war that in May 2000 prompted the unilateral withdrawal of Israeli forces from south Lebanon, ending its eighteen-year-long occupation,” says CFR Senior Fellow Bruce Hoffman. “Thereafter, Hezbollah effectively supplanted the Lebanese Army as the country’s only truly effective military force. Moreover, Nasrallah’s commanding authority and popularity among most Lebanese—Sunni, Christian, and Shi’a alike—was cemented.

As leader, Nasrallah oversaw the seven-member Shura Council and its five subcouncils: the political assembly, the jihad assembly (military body), the parliamentary assembly, the executive assembly, and the judicial assembly. “Nasrallah’s death is a crushing blow,” writes Hoffman, “there are no clear successors to Nasrallah given his unique and unrivaled stature at the top of the movement.”

How is Hezbollah led and organized?

Following Nasrallah’s death, some speculated that Naim Qassem, Hezbollah’s deputy secretary-general and acting interim leader, or Hashim Safieddine, another senior leader, could replace him atop the group. However, the Israeli military killed Safieddine and several other Hezbollah militants in a Beirut air strike in early October. Qassem’s whereabouts are unclear, although a recent report indicated he fled Beirut for refuge in Tehran. 

“With its leadership effectively decapitated and its communications compromised,” said Hoffman after Nasrallah’s death, “Hezbollah for the time being will have trouble mobilizing to engage in any kind of effective and sustained combat with Israel.” 

Hezbollah controls much of Lebanon’s Shiite-majority areas, including parts of Beirut, southern Lebanon, and the eastern Bekaa Valley region. Although Hezbollah is based in Lebanon, its manifesto states that its operations, especially those targeting the United States, are not confined by domestic borders: “The American threat is not local or restricted to a particular region, and as such, confrontation of such a threat must be international as well.” The group has been accused of planning and perpetrating acts of terrorism against Israeli and Jewish targets abroad, and there is evidence of Hezbollah operations in Africa, the Americas, and Asia.

What role has it played in Lebanese politics?

Hezbollah has been a fixture of the Lebanese government since 1992, when eight of its members were elected to Parliament, and the party has held cabinet positions since 2005. The party marked its integration into mainstream politics in 2009 with an updated manifesto that was less Islamist than its predecessor and called for “true democracy.” The most recent national elections, in 2022, saw Hezbollah maintain its 13 seats in Lebanon’s 128-member Parliament, though the party and its allies lost their majority. Lebanon has had a caretaker government with limited powers since October 2022. 

Hezbollah essentially operates as a government in the areas under its control, and neither the military nor federal authorities can counter this, Arab Barometer analysts MaryClare Roche and Michael Robbins wrote for Foreign Affairs in July 2024. It manages a vast network of social services that include infrastructure, health-care facilities, schools, and youth programs, all of which have been instrumental in garnering support for Hezbollah from Shiite and non-Shiite Lebanese alike. Even so, Arab Barometer polling in 2024 found that “despite Hezbollah’s significant influence in Lebanon, relatively few Lebanese support it.”

What is Hezbollah’s military role and weapons arsenal?

Hezbollah is the dominant military force in Lebanon. Its fighting strength is difficult to assess amid the ongoing conflict with Israel that has devastated the group’s leadership and significantly eroded its rank-and-file. In 2021, Nasrallah said the group had 100,000 fighters, although analysts say this could have been an exaggerated figure. In 2022, the U.S. State Department estimated [PDF] that there were “tens of thousands of supporters and members worldwide.” Other more recent analysts have put the number at roughly 40,000–50,000. 

Under the 1989 Taif Agreement, which ended Lebanon’s civil war, Hezbollah was the only militia allowed to keep its arms. Security analyst and ex-Israeli general Assaf Orion says Hezbollah possesses “a larger arsenal of artillery than most nations enjoy,” and a 2018 report from the Center for Strategic and International Studies called it “the world’s most heavily armed non-state actor.” In June 2024, experts speculated that Hezbollah had 150,000–200,000 rockets and missiles of various ranges.

Iran provides most of Hezbollah’s training, weapons, and funding, sending the group hundreds of millions of dollars each year, according to the State Department. Hezbollah also receives some support from the Bashar al-Assad regime in Syria, as well as financing from legal businesses, international criminal enterprises, and the Lebanese diaspora.

Critics say Hezbollah’s existence violates UN Security Council Resolution 1559—adopted in 2004—which called for all Lebanese militias to disband and disarm. The UN Interim Force in Lebanon (UNIFIL), first deployed in 1978 to restore the central government’s authority, remains in the country and part of its mandate is to encourage Hezbollah to disarm.

The Lebanese Armed Forces (LAF), the country’s all-volunteer conventional military, numbers about 80,000 troops and draws recruits from Lebanon’s various religious communities. But regional analysts say it has limited resources for national defense and focuses primarily on maintaining domestic stability. The United States has viewed the LAF as a stabilizing counterweight to Hezbollah, providing it with some $3 billion in aid since 2006.

What is Hezbollah’s connection to Syria?

Hezbollah finds a loyal ally in Syria, whose army occupied most of Lebanon during Lebanon’s civil war. The Syrian government remained as a peacekeeping force in Lebanon until it was driven out in the 2005 Cedar Revolution, a popular protest movement against the foreign occupation. Hezbollah had unsuccessfully pushed for Syrian forces to remain in Lebanon, and has since remained a stalwart ally of the Assad regime. In return for Tehran’s and Hezbollah’s support, experts say, the Syrian government facilitates the transfer of weapons from Iran to the militia.

Hezbollah publicly confirmed its involvement in the Syrian Civil War in 2013, and it sent some seven thousand militants to assist Iranian and Russian forces in supporting the Syrian government against largely Sunni rebel groups. Hezbollah withdrew many of its fighters in 2019, attributing the decision to the Assad regime’s military success. Analysts say fighting in Syria helped Hezbollah become a stronger military force, while some Lebanese complain that focusing on the war led the group to neglect its domestic duties. Hezbollah’s support from Sunnis in particular has waned over the group’s backing of the Assad regime. Hezbollah’s involvement in the war also opened it to further attacks by Israel, which regularly launches air strikes against Iran-allied forces in Syria.

Where does it stand on Israel?

Israel is Hezbollah’s main enemy, dating back to Israel’s occupation of southern Lebanon in 1978. Hezbollah has been blamed for attacks on Jewish and Israeli targets abroad, including the 1994 car bombings of a Jewish community center in Argentina, which killed eighty-five people, and the bombings of the Israeli Embassy in London. Even after Israel officially withdrew from southern Lebanon in 2000, it continued to clash with Hezbollah, especially in the disputed Shebaa Farms border zone. Periodic conflict between Hezbollah and Israeli forces escalated into a monthlong war in 2006, during which Hezbollah launched thousands of rockets into Israeli territory.

The group reiterated its commitment to the destruction of the Israeli state in its 2009 manifesto. In December 2018, Israel announced the discovery of miles of tunnels running from Lebanon into northern Israel that it claimed were created by Hezbollah. The following year, Hezbollah attacked an Israeli army base—the first serious cross-border exchange in more than four years. In August 2021, Hezbollah fired more than a dozen rockets in response to Israeli air strikes in Lebanon; it was the first time the group claimed responsibility for rockets fired into Israel since the 2006 Israel-Hezbollah war.

How have the United States and other countries treated the group?

U.S. policymakers see Hezbollah as a global terrorist threat. The Bill Clinton administration designated Hezbollah a foreign terrorist organization in 1997, and several individual Hezbollah members, including Nasrallah, are labeled “specially designated global terrorists,” which subjects them to U.S. sanctions. In the mid-2010s, the Barack Obama administration provided aid to Lebanon’s military with the hope of diminishing Hezbollah’s credibility as the country’s most capable military force. However, Hezbollah’s and the Lebanese military’s parallel efforts to defend the Syrian border from the Islamic State and al-Qaeda-affiliated militants made Congress hesitant to send further aid [PDF], for fear that Hezbollah could acquire it.

In 2015, the U.S. Congress passed the Hizballah International Financing Prevention Act, which sanctions foreign institutions that use U.S. bank accounts to finance Hezbollah. Lawmakers amended it in 2018 to include additional types of activities. Additionally, the Donald Trump administration sanctioned some of Hezbollah’s members in Parliament as part of its “maximum pressure” campaign against Iran. While Trump’s approach disrupted Iran’s economy, analysts say the country’s increasingly self-sufficient proxies have weathered the worst of the sanctions.

President Joe Biden’s administration has continued sanctioning individuals connected to Hezbollah’s financing network, including Ibrahim Ali Daher, head of the group’s Central Finance Unit. In 2021, the Treasury Department announced sanctions targeting an international finance network accused of laundering tens of millions of dollars through regional financial systems to benefit Hezbollah and Iran.

The European Union (EU) has taken a less aggressive approach to Hezbollah. The bloc designated Hezbollah’s military arm a terrorist group in 2013 over its involvement in a bombing in Bulgaria and its backing of the Assad regime. In 2014, the EU’s multinational police agency, Europol, and the United States created a joint group to counter Hezbollah’s terrorist activities in Europe. In recent years, several European countries have taken a stronger stance. The United Kingdom deemed all of Hezbollah a terrorist group in 2019, followed by the German government in 2020.

Hezbollah has scorned the largely Sunni Gulf Arab countries over their relations  with the United States, Israel, and European powers. The Gulf Cooperation Council—comprising the seven Arab states of the Persian Gulf, with the exception of Iraq—considers Hezbollah a terrorist organization. Additionally, Saudi Arabia and the United States co-lead the Terrorist Financing Targeting Center, created in 2017 to disrupt resource flows to Iran-backed groups such as Hezbollah.

What’s happened amid the Israel-Hamas war?

Following Hamas’s October 2023 assault on Israel, the Iran-backed Palestinian militant group based in the Gaza Strip, Hezbollah began firing rockets, mortars, and drones across the Israel-Lebanon border in a show of what the group’s leaders called “solidarity” with its militarily inferior ally. The attacks have forced some 60,000 Israelis to flee their homes in the country’s north.

Hezbollah-Israel, and Iran-Israel clashes have only intensified in 2024, fueling concerns of a wider regional war. Israel blamed Hezbollah for a missile strike in the Golan Heights in late July that killed twelve children, an attack that the group denies. Israel responded shortly after by targeting Fuad Shukr, a senior Hezbollah commander in Beirut, in a strike that also reportedly killed three civilians and wounded dozens more.

In September, Israel ramped up air strikes on Hezbollah military infrastructure in Lebanon and is suspected of conducting thousands of coordinated bombing attacks against Hezbollah members, remotely detonating their private electronic devices. An Israeli air strike killed longtime group leader Hassan Nasrallah on September 27. Days after, Israel launched a ground invasion of southern Lebanon, aiming to drive Hezbollah from the border region and allow displaced Israelis to return home. Israel has said it is effectively a military campaign to enforce a UN Security Council resolution from 2006, which called for a withdrawal of all armed personnel, except for the LAF and UNIFIL, from a portion of southern Lebanon. Lebanese authorities in late October said Israel’s heavy bombardments, some of which have leveled entire buildings in Beirut, had killed more than 2,500 people and displaced more than one million since it stepped up its campaign against Hezbollah in late September.

Kali Robinson and Jonathan Masters contributed to this Backgrounder.