The short-lived ceasefire between Iran and Israel was unravelling on Tuesday, stoking fears of a revived conflict and a cornered Tehran deploying its fearsome proxies to fight for the regime's survival. US President Donald Trump slammed Israel and Iran for violating a ceasefire aimed at ending days of American and Israeli strikes on Iran's nuclear sites, and retaliatory Iranian strikes against both powers. As that deal collapses, the focus returns to Iran, and whether its Islamist military elite can hold on to power and is willing to abandon its alleged nuclear weapons program in exchange for peace.

Iranian groups that could strike back at America

Ayatollah Ali Khamenei is reportedly holed up in a bunker, struggling to communicate with a government losing confidence in its supreme leader. Analysts are divided over whether he will seek a deal or go on the offensive. The regime's Islamic Revolutionary Guard Corps (IRGC) has lost top brass in Israeli strikes, but still has 190,000 personnel and its elite Al Quds Force to launch attacks overseas, including via Hezbollah, the Houthis and other surrogates.

The Pentagon has some 40,000 US troops operating from 19 bases in the region, which are braced for more attacks like Monday's Iranian strike on Al Udeid Air Base, in Qatar. Israel, other Gulf Arab states, and Gulf shipping, are also likely targets. The US Department of Homeland Security has warned of a 'heightened threat environment', citing the risk of cyber-attacks and violence. Police in big US cities stepped up patrols with a focus on religious, cultural and diplomatic sites. The Daily Mail looks at the dangerous groups that could strike back at America in the coming weeks.

The Quds Force

Size: 20,000 (estimate). Location: Iran, operates globally. Leader: In flux. At the heart of Tehran's global war machine is the Quds Force, the elite wing of the IRGC, tasked with foreign operations. It is named after the Arabic word for Jerusalem, and is likened to a spy agency with commando units. With decades of experience funding, training and arming foreign fighters, the Quds Force is Tehran's go-to instrument for asymmetric warfare. Analysts say it is likely coordinating Iran's response, selecting targets across the region and beyond. The force built up a network of Arab allies known as the Axis of Resistance, establishing Hezbollah in Lebanon in 1982 and supporting the Palestinian militant Islamist group Hamas in the Gaza Strip.

Quds Force leaders have in recent years plotted to bomb Israeli and Saudi embassies in Washington, and been involved in assassination plots against Republican hawks John Bolton and Mike Pompeo, along with a Saudi ambassador to the US. Intelligence chiefs fear that Quds Force already has 'sleeper' cells operating in the US homeland. Some 729 Iranian nationals were reportedly allowed into the US between 2021 and 2024, under the Biden administration's relaxed border rules. Still, the group has faced devastating setbacks. Its leader brigadier general Esmail Qaani was reportedly killed in an Israeli strike on June 13. His infamous predecessor Qassem Soleimani died in a 2020 US drone strike.

Hamas

Size: 20,000 (estimate). Location: Palestinian territories. Leader: In flux. The Palestinian group Hamas was quick to condemn US strikes on Iran's nuclear facilities, branding Washington and its regional ally Israel 'fully responsible for the grave repercussions of this aggression.' Yet while Hamas expressed 'solidarity' with Tehran in its official response, it swerved away from that fight, saying it had 'complete confidence in Iran's ability to defend its sovereignty and the interests of its people.'

Hamas is not the force it was before it launched its coordinated Oct. 7, 2023, raids on southern Israel, and invited Israel's ferocious military onslaught on the militants and blameless Gaza residents alike. Virtually all of Hamas' senior leaders have been killed, and it remains unclear whether the group can still mount major attacks on Israel. Israel says it has killed some 20,000 militants in Gaza. US officials in January said Hamas had recruited as many as 15,000 fighters since the war began, though many were young and untrained. Hamas is a Sunni militant group focussed on a land dispute with Israel. It only ever had moderate ties with Shiite Iran. Hamas leaders expressed 'disappointment' at the lackluster support they received from Axis allies against Israel.

Hezbollah

Size: 50,000 (estimate). Location: Southern Lebanon. Leader: Naim Qassem. Hezbollah was once seen as the 'crown jewel' of Iran's surrogates and the most deadly member of the 'ring of fire' to attack Israel in the event of war between the Jewish state and Iran. But much has changed since Hamas's October 2023 raids, and Israel's military response in Gaza and then against Hezbollah in Lebanon, involving everything from airstrikes to exploding pagers.

The group is understood to be well short of the 100,000 fighters it boasted of in 2021. It faces regular Israel strikes and commando raids, and has not launched a single attack on Israel since its latest bombardment of Iran began. A spokesperson for Hezbollah told Newsweek that the group did not have immediate plans to retaliate against Israel and the US over their strikes on Iran's nuclear program, saying Iran was a 'strong country capable of defending itself.' 'Logic dictates that it can confront America and Israel,' added the spokesperson. Still, US intelligence agencies remain alarmed by Hezbollah's worldwide footprint of terrorist cells, including militants who could have crossed America's southern border to launch attacks on US soil.

The Houthis

Size: 10,000 - 30,000. Location: Yemen. Leader: Abdul-Malik Al Houthi. With Hamas and Hezbollah on the ropes, the rebel Houthi armed movement in Yemen is the Tehran-aligned group perhaps best positioned to forcefully respond to the US and Israeli airstrikes on Iran. Since the weekend attacks, the Houthis have vowed to support Iran in its fight and called for Muslim states to join the 'Jihad and resistance option as one front against the Zionist-American arrogance.' Yet while the Houthis have a track record of long-range drone strikes on Israel and missiles on shipping containers transiting the nearby Red Sea, these do not appear to have restarted amid the current escalation.

The Houthis are still technically bound by a ceasefire they struck with the US in May - Washington stopped its military campaign against the Houthis in exchange for the group halting attacks on US interests in the region. The Houthis, too, have seen their missile and other military assets in Yemen pounded by Israeli warplanes for months, along with US and British strikes aimed at reducing the Houthi threat to shipping in the region. While the Houthis have received arms and training from Iran over the years, they follow a different branch of Islam, are geographically isolated, and are chiefly focussed on their country's 11-year civil war.

Syria and Iraq

Sizes: Various groups from 3,000 - 60,000. Location: Syria and Iraq. Leader: Various. In terms of raw manpower, Iran's proxy strength is perhaps greatest across Iraq, and to a lesser extent in Syria. Tehran has strong ties to nearly a dozen armed groups there, some with as many as 60,000 fighters. Among the most formidable are Kata'ib Hezbollah, an Iraqi Shia Islamist paramilitary group founded in 2003 to fight off US-led forces there, and the Badr Organization, which was formed in the years after the 1979 Islamic Revolution.

Kata'ib Hezbollah has a record of attacking US bases, at the behest of Iran. Its commander Abu Ali al-Askari has threatened to target US bases over its attack on Iran, telling CNN that they 'will become akin to duck-hunting grounds.' Still, these Shiite groups are also focussed chiefly on their local concerns. Iran in the past wielded great influence in Syria, thanks to its President Bashar Al Assad's growing reliance on Tehran to prop up his embattled government. Tehran's influence in Syria collapsed after Assad's regime imploded in December and Sunni rebels seized control of the country. Crucially, this denied Iran a land route to supply missiles to Hezbollah in Lebanon.