From Hamas to Hezbollah, a look at the Iran-allied groups rallying to arms around Middle East

Hezbollah has fired a volley of rockets towards Israel in the latest effort by an Iran-backed militia to attack the country since it launched its retaliatory offensive in Gaza last October.

The  Lebanese group said it had fired 320 Katyusha rockets towards Israel and hit 11 military targets in what it called the first phase of its retaliation for Israel’s assassination of Fuad Shukr, a senior commander, last month.

Israel’s military said it had foiled a much larger attack with pre-emptive airstrikes after assessing that Hezbollah was preparing to launch the barrage, using 100 jets to strike more than 40 Hezbollah launch sites in southern Lebanon.

The strikes destroyed thousands of launcher barrels, aimed mostly at northern Israel but also targeting some central areas, Israel’s military said.

While Hezbollah is distinct from the Hamas militia in charge of the Gaza Strip, the two groups are strong allies who are both backed by Iran as part of Tehran’s shadow war against Israel.

While Hamas has been fighting a war with Israel in Gaza for nearly a year, with more than 40,000 Palestinians killed as a result, Hezbollah says it has attacked Israel in solidarity with their allies in the nearby enclave.

They are not the only group fighting alongside Hamas, though they are the most powerful.

Below, we have put together a breakdown of the armed groups facing Israel and the United States in the Middle East, a look at what unites some of them, and what's different about each.

Israel and the US have been battling a range of armed groups that are allied to Iran and to each other. They are:

All the groups have escalated attacks on US, Israeli or global targets within their reach since Israel launched its war in Gaza on 7 October, after Hamas's deadly cross-border raids that killed 1,200 people and led to 251 more being taken captive in the enclave. Around half of those are still being held hostage in Gaza.

The aim of Iran and the armed groups at large is to aid Hamas with attacks that distract the focus of Israel and the US, and that make the military, economic and political costs of continuing the war against Hamas too great for Israel and the US.

The groups don't necessarily want further additional escalation themselves, given their odds in any all-out confrontation with two of the world's strongest militaries, experts say. But under the leadership of the late Iranian Gen. Qassem Soleimani, who was killed by the US in 2020, the far-flung array of Iranian-allied militias knitted themselves into a more cohesive network.

They also grew into a common understanding, said Randa Slim, a regional analyst with the Washington-based Middle East Institute: When the survival of any one was threatened, all would rally.

What: Based in Gaza. Founded in 1987 at a time of widespread protests by Palestinians against Israel’s occupation. Has early ties to one of the Sunni world’s most prominent groups, the Muslim Brotherhood, founded in Egypt in the 1920s. It has vowed to annihilate Israel and has carried out suicide bombings and other deadly attacks on civilians and Israeli soldiers.

Background: Hamas seized control of Gaza by force in 2007, the year after it won parliamentary elections there with 44% of the vote. Israel has kept Gaza under a devastating blockade ever since, restricting the movement of people and goods in and out of the territory. Hamas receives backing from Arab and Muslim countries, including Qatar and Turkey. Although a Sunni Muslim group, Hamas leaders have moved closer to Shiite Muslim Iran and its allies over the years. Hamas's October 7 attacks in Israel were seen by many as Hamas's bid to reclaim relevance on the world stage. Israel's far-right government had sidelined any attempt at a negotiated Israeli-Palestinian political agreement, and world attention faded away.

What: Formed in 1982 in response to the Israeli invasion of Lebanon, where it is based. One of the strongest members of the Iran-allied alliance, militarily and organizationally. A Shiite Muslim group. Took part in repeated attacks against the US through the mid-1990s, including the deadly 1983 bombing of a US Marines barrack in Beirut, Lebanon's capital. Has participated in Lebanon's government since 1992. Its military wing is stronger than the country's armed forces.

Background: A 2006 war with Israel provoked by Hezbollah's kidnapping of Israeli soldiers devastated southern Lebanon and Beirut. Many ordinary Lebanese are deeply fearful of a new war with Israel in the wake of the Gaza fighting. Wary of a repeat of the war itself, Hezbollah has lobbed rockets and missiles across its southern border into Israel since the start of the war in Gaza, losing fighters daily in return fire, but held back from further dramatic escalation. That may have changed with a presumed Israeli strike this week that killed a Hamas leader sheltering in Lebanon. Hezbollah leader Hassan Nasrallah said Friday that his group had to retaliate, or else all of Lebanon would be vulnerable to Israeli attack.

What: Based in Yemen, overseeing one of the world's most vital shipping routes for oil and other trade. Have launched rockets, missiles and drones at commercial vessels during the Gaza war. Forced some major shippers to change route and threatens a potentially major toll on the world's economy. Formally known as Ansar Allah. Had its start as one of several armed groups vying internally for power in fractured, impoverished Yemen. While Shiite Muslim, it's of a different branch than Iran. The group's motto calls for the destruction of Israel and the US, though it has been largely focused on affairs in Yemen.

Background: At odds with Yemen's government, Houthis seized control of Yemen's capital in 2014 and soon controlled much of the north. After Saudi Arabia and the United Arab Emirates opened an attack in 2015 in an unsuccessful attempt to rout the Houthis, the Houthis moved increasingly close to Iran as a source of materiel support.

Saudi and US attempts to formally end the Saudi-led war in Yemen have failed to bring Yemen's war to a close but had succeeded in stopping what were sporadic missile and drone strikes by the Houthis against their richer Gulf neighbors. The Houthis, who have limited popular support in Yemen outside of their immediate base, are seen as more independent of Iran in their actions than some of the other groups in the alliance. The strikes on shipping since Israel launched its campaign in Gaza are some of the Houthis' first outward-facing attacks, other than at its Gulf enemies.

What: Array of smaller Iranian-backed militant groups that have battled with US and coalition forces in Iraq and Syria for years. Mount sporadic attacks against bases in the region where US troops are deployed to fight Islamic State group insurgents.

Background: There has been a dramatic spike in attacks by Iran’s proxies in those two countries since the opening of the war between Israel and Hamas. Iraq says it is working with the US to contain the militias there. On Thursday, the US unleashed an airstrike against the headquarters of an Iran-backed militia in central Baghdad, killing a high-ranking militia commander. It was an attempt to discourage more attacks.

What: Israel's deadly military campaign in Gaza, and the US’s support for it, are sparking calls to action by violent extremist groups that have long battled the West and other enemies.

Background: On Thursday, a spokesman for the Islamic State called on Muslims around the world to carry out killings in what he said would be vengeance for the people of Gaza. “Oh lions of Islam, hunt your prey — the Jews, Christians, and their allies — in the streets and alleyways of America, Europe, and the world,” Abu Hudhayfa al-Ansar said in a speech transcribed by the SITE intelligence group. “Break into their homes, kill them, and torment them in every way you can.”