On March 7, Saudi Arabia took the extraordinary step of declaring the Muslim Brotherhood a terrorist organization, on par with Hezbollah and al Qaeda. The move came just two days after the kingdom, together with the United Arab Emirates and Bahrain, withdrew its ambassador from Qatar because of Qatar’s alleged support of Brotherhood interference in internal politics. Although Saudi Arabia’s dislike of Brotherhood political activities abroad is well known, for decades the kingdom has tolerated (and sometimes even worked with) the local Saudi branch of the Brotherhood. Its sudden reversal is an expression of solidarity with its politically vulnerable allies in the region and a warning to Sunni Islamists within its borders to tread carefully.

This story goes back to the Arab Spring, when Egyptian President Hosni Mubarak, Saudi Arabia’s longtime ally, was ousted, and Egypt elected Mohamed Morsi, a Muslim Brotherhood­–linked politician, to fill his shoes. Riyadh feared that the group, now empowered, would try to export the Egyptian revolution regionwide, calling for action against the House of Saud and displacing Saudi’s friends and allies such as the UAE. Those fears were not entirely unfounded.

In Saudi Arabia, members of the Muslim Brotherhood had been at the forefront of the Awakening movement, a push in the early 1990s for political change in response to alleged Saudi government corruption and the basing of U.S. troops in the country. But, as the political science professor Stéphane Lacroix documents in his book Awakening Islam, most members of the Saudi Muslim Brotherhood had quickly fallen into line once the regime began to arrest or sanction its leaders. The Saudi Brotherhood simply had too much to lose: its members helped build the Saudi state and occupied important positions in the religious and educational establishment.

That détente ended with the Arab Spring, when a number of prominent Islamists added their names to a 2011 petition calling for political reforms in the kingdom. They also obliquely criticized the lack of political freedom in Saudi Arabia by lavishing praise on fellow travelers in Tunisia and Egypt. Even Nasir al-Umar, a hard-line Sururi (a blend of Brotherhood and ultraconservative Salafism), was singing the praises of democratic change. Then Crown Prince Nayef and future Crown Prince Salman pressed them into silence. According to one person I spoke to on a recent trip to Saudi Arabia, some were forced to sign a pledge to cease criticizing the lack of political freedom in the kingdom. But the renewed détente was fragile, hinging on events in tumultuous Egypt.

There was some reason for Saudi Arabia to fear for its allies in the region as well. Under Mubarak, Egypt had been a dependable Saudi ally. But Morsi sought to chart a neutral course between Saudi Arabia and Iran, following an early fundraising visit to the kingdom with an attempted rapprochement with Iran. The United Arab Emirates was worried, too. The Brotherhood has had a small presence in UAE since the 1960s, but after 9/11 the government started to see the group as a national security threat. It didn’t help that when the Muslim Brotherhood came to power in Egypt some members of the UAE branch began agitating for political reforms, going so far as to sign a petition calling for elections and real authority for the UAE’s advisory council. The government responded by arresting group members across the country, including men belonging to an alleged terror cell with ties to the Muslim Brotherhood in Egypt.

In response to what they saw as Egyptian meddling, Saudi Arabia tried to economically isolate Morsi and hasten his departure. In May 2013, just two months before the military overthrow of Morsi, the Egyptian finance minister complained to the Saudis that Egypt had only received $1 billion of the $3.5 billion in aid promised after Mubarak’s downfall. When the Egyptian military overthrew Morsi just a year into his rule, Saudi Arabia applauded and quickly promised Egypt a new aid package of $5 billion, together with one from the UAE for $3 billion and from Kuwait for $4 billion. When the new regime massacred Brotherhood protestors in August, the taciturn King Abdullah uncharacteristically voiced his public support for the slaughter as a blow against terrorism. When the new Egyptian government declared the group a terrorist organization in late December 2013, Saudi Arabia followed suit. When UAE decided not to replace its departing ambassador in Qatar -- partly to punish Qatar for its refusal to discipline an influential Qatar-based Brotherhood spiritual leader who preached that the UAE is against Islamic rule -- Saudi Arabia recalled its own ambassador in solidarity.

Saudi Arabia’s moves have provoked some unhappiness at home. Saudi Islamists, particularly the Brothers, are convinced that Morsi’s overthrow was part of a Saudi plot to roll back Islamist political gains of the past three years. In defiance, they festooned their social media profiles with symbols of Brotherhood resistance and criticized their government for its complicity. The defiance has become more muted recently, after the local press reported that the government was contemplating declaring the Brotherhood a terrorist organization. According to former members of the Saudi Muslim Brotherhood I spoke with, the 25,000 or so members of the Brotherhood in Saudi Arabia reacted to the news of the deliberations by preemptively keeping a low profile, closing some of its gatherings so as not to further stoke the government’s ire. Until the Saudi government actually begins making arrests, its recent announcement is more of a shot across the Brotherhood’s bow than an attempt to sink the ship.

Nevertheless, person after person I interviewed asserted that the level of Islamist anger toward the Saudi government is higher than at any time since the early 1990s. That does not mean Brotherhood leaders will move against the regime in the near term. In the 1990s as now, they have too much to lose institutionally. There is also some benefit in a wait-and-see approach, which is why Salman al-Awda, a prominent Saudi Islamist, is privately counselling his followers to wait for the regime’s factions to sort things out among themselves. But the younger rank-and-file Brothers in Saudi, like those in other Brotherhood franchises outside Egypt, are starting to lose hope in peaceful political change. That frustration can lead to apathy. But it can also lead to violence -- and if it does, the Saudi government’s decision to declare the group a terrorist organization will have been a self-fulfilling prophecy.