After spending over a week in Saudi Arabia following his unexpected resignation, then visiting France, Saad Hariri, Lebanon’s former prime minister, is expected to arrive back in Lebanon later today. He has accused ^[1] Iran of using Hezbollah to create a ‘state within a state’. Hariri painted a picture of a Lebanon like the one in 2005, when his father and other prominent politicians and journalists were assassinated.

The Lebanese political system is highly fragile because it operates through a sectarian power-sharing system—the prime minister must be a Sunni, the president a Maronite Christian and the parliamentary speaker a Shia.

Hariri’s older brother, Bahaa, is reportedly in Saudi Arabia, sparking rumours that he’ll take control of the Future Movement, the political party that Saad had been leading because, to the Saudis, Saad is tainted by his association with Hezbollah. There are serious questions about whether Bahaa could manage the tricky Lebanese political system. He, too, would need to work with Hezbollah, which is unlikely to support him if he’s openly pro-Saudi, anti-Iran and anti-Assad.

Hezbollah has repeatedly shown that any attempt to challenge its control of southern Lebanon or limit its power within Lebanon would lead to a political crisis. It is a hybrid terrorist organisation ^[2] that uses its military muscle (it has a militia of 30,000 men) and social, religious and economic power to ensure that it can’t be ignored. For example, in 2011, Saad Hariri’s unity government collapsed when Hezbollah withdrew from the coalition because four of its members were accused of involvement in the 2005 assassination of Hariri’s father, Rafik. And in 2014, when Michel Suleiman stepped down as Lebanon’s president, Hezbollah wouldn’t support any candidate who was hostile to it and its engagement in the Syrian civil war, leaving the country without a president for 20 months.

For the Iranians, Hezbollah is key because of its 10,000 rockets, which are aimed at Israel. The rockets are a daily reminder to the Israelis that an air assault on Iran would lead to a massive rocket onslaught on northern Israel, as was the case in the 2006 war. Moreover, the Iranians have used Hezbollah to support the Assad regime, which gives Iran plausible deniability when it comes to accusations that it is a state sponsor of terrorism.

Many of the explanations for the latest political crisis in Lebanon relate to the unfolding of Saudi–Iran competition. Crown Prince Mohammed bin Salman—who is expected ^[3] to become king in the next few weeks as his ailing father steps down—has a dual agenda of radically reforming Saudi Arabia and challenging Iran’s growing dominance. That agenda has meant that Lebanon has become crucial to the new administration in Riyadh, which is no longer prepared to see Iran extending its influence. (As part of his campaign to oppose Iranian adventurism, bin Salman committed Saudi Arabia to fight the Houthis in Yemen.)

Saad Hariri became prime minister through a power-sharing agreement orchestrated by President Michel Aoun, a Hezbollah supporter. It’s possible that Hariri agreed to work with Aoun because he assumed that the Saudis would stand by his decision to put country before regional politics ^[4] (the agreement was reached before bin Salman assumed power over Saudi domestic and foreign policy). However, when bin Salman gained control, he wasn’t going to tolerate Hezbollah leading in Lebanon because that would also mean that Tehran would have created an arc of influence stretching all the way to the eastern Mediterranean. By agreeing to serve as prime minister with Aoun, Hariri legitimised Hezbollah’s role in Lebanon, thereby becoming an impediment to bin Salman’s Lebanon strategy.

When bin Salman looks at Lebanon, what he sees is either another Iranian satellite or the possibility of an Iranian satellite. It’s likely that bin Salman would have noticed that the Lebanese government refused to condemn attacks on the Saudi embassy in Tehran in January 2016, and in 2015 actually arrested ^[5] a Saudi prince at Beirut airport with two tons of amphetamines on his private plane.

The challenge for bin Salman is that, unlike Iran, Saudi Arabia doesn’t have a military proxy in Lebanon. Therefore, the only tool that Riyadh has for exerting pressure is economics: around 400,000 Lebanese ^[6] work in the Gulf and their remittances amount to 20% of the Lebanese economy, which the Saudis also support financially.

The Saudis wield enormous pressure over the Hariri family. The Hariri family construction company, Saudi Oger, is reportedly owed around US$9 billion ^[7] by the Saudi government. The company is apparently no longer operating ^[8], having collapsed owing at least US$3.5 billion to Saudi banks.

With Saad Hariri out of office—and with a US administration that’s so hostile to Tehran that it’s willing to undermine international nuclear non-proliferation efforts ^[9], and a right-wing Israeli government that’s been beating the anti-Iran drum for years and is willing to share intelligence with the Saudis ^[10]—the Saudis can now concentrate on challenging the Iranians.