For the United States, revolution in Saudi Arabia would be a game changer. While the U.S. can live without Saudi oil, China, India, Japan, and Europe cannot. Any disruption in Saudi oil exports—whether due to unrest, cyberattacks, or a new regime’s decision to reduce exports substantially—will have a major impact on the global economy. In addition, the CIA war against al Qaeda is heavily dependent on the kingdom: Saudi intelligence operations foiled the last two attacks by al Qaeda in the Arabian Peninsula on the American homeland. The U.S. military training mission in the kingdom, founded in 1953, is the largest of its kind in the world. The Saudis also have been a key player in containing Iran for decades.

The other monarchs of Arabia, meanwhile, would be in jeopardy if revolution comes to Saudi Arabia. The Sunni minority in Bahrain could not last without Saudi money and tanks. Despite all their money, Qatar, Kuwait, and the United Arab Emirates are city states that would be unable to defend themselves against a revolutionary regime in what had been the kingdom. The Hashemite dynasty in Jordan would be at risk as well without Saudi and Gulf money and oil. Only Oman is probably isolated and strong enough to endure.

America has no serious options for effecting gradual reform in the kingdom. The Saudis fear, probably rightly, that real power sharing is impossible in an absolutist state. But we should plan very quietly for the worst. The intelligence community should be directed to make internal developments, not just counterterrorism, its top priority in the kingdom now. We cannot afford a surprise like Iran in 1978, and we need to know the players in the opposition, especially the Wahhabi clerics, in depth. This will be a formidable challenge, but it is essential to preparing for a very dark swan.