Explainer: Who are Iran's proxy forces, and what part did they play in the attack on Israel?

Amid fears that the aerial assault could represent the opening of a bloody new chapter in the Middle East’s history, Iran knows that it has a lack of regional diplomatic clout. Its most important state ally is Syria, a country left weakened by a gruelling and bloody civil war. While Iran has deepened their military cooperation with Russia in recent months, with Moscow believed to be helping Iran to improve its air defence systems, the ongoing war in Ukraine means it is unlikely Moscow would be in a position to offer significant assistance should the situation escalate.

Instead, it is the network of Iranian proxy forces across the Middle East, an informal coalition known as the axis of resistance, that is best placed to fight alongside Tehran should the situation escalate. Although Iran does not exert day-to-day operational control over any of its proxies, the extent of its influence - it provides funding, weapons, and training - has partly overcome Sunni-Shia religious divides, and helped Iran bolster its position. That was laid bare by the fact that several groups joined in the attack on Israel.

The most powerful of those is Hezbollah in Lebanon, which claimed to have fired dozens of rockets at Israeli army positions in the Golan Heights, soon after Iran launched its own barrage of missiles and drones. It praised Iran’s unprecedented aerial assault, describing it as a “brave” decision that initiated a “new phase” of the conflict with Israel.

Hezbollah fighters have been engaged in battles with Israeli forces almost continuously since the war between Israel and Hamas - a group which also receives backing from Shia-led Iran, despite the fact it is primarily a Sunni Muslim entity - broke out. With hundreds of millions of pounds coming in from Iran every year, according to US officials, and a significant arsenal at its disposal, including long-range and precision guided missiles, it has both the means and the will to ramp up the conflict. A separate group, Palestinian Islamic Jihad, is also closely linked to Iran.

Another key ally is the Houthi rebel group in Yemen, which is understood to have launched multiple drones against Israel as part of the coordinated attack earlier this week. It too has shown support for Hamas since the war began six months ago, firing numerous missiles and drones towards Israel, and attacking commercial shipping targets in the Red Sea.

Elsewhere, fighters from Shia Muslim-majority countries such as Iraq also form part of Iran’s proxy force, with the Kata’ib Hezbollah militia suspected of a drone strike in north-eastern Jordan that killed three US soldiers earlier this year. Other Iraqi groups aligned with Iran include the Badr Organisation and Asa’ib Ahl al-Haq, although the extent of Tehran’s influence over them is unclear. In Bahrain, too, militias such as the Al Ashtar Brigades and Saraya al Muktar form part of the Iranian axis.