Rulers of the nations along the Arabian Peninsula bet decades ago that they could use oil sales to build thriving modern societies. They aimed to lure expats from around the world in search of work, security, and warm weather. Anyone who has visited Dubai or Doha knows how successfully that worked out—the region’s population has more than doubled in the past 30 years, to about 60 million, and huge increases are predicted.Now the Iran war has put that ambition’s greatest vulnerability front and center. The scorching, oil-rich desert sands have precluded the development of much, if any, agriculture, forcing governments to rely almost entirely on imported food. Most of those imports arrive through the Strait of Hormuz, the slender waterway that is now effectively closed to commercial shipping because of the threat of mines and drone attacks from Iranian forces and their proxies.“Of course we’re worried,” one official from a member of the Gulf Cooperation Council, which comprises Saudi Arabia, Oman, United Arab Emirates, Qatar, Kuwait, and Bahrain, told me. Like others I spoke with, he was reluctant to go further precisely because he didn’t want to call attention to such an existential issue. Another said only that he hoped the war would end soon.The numbers show the scale of the threat. Last year, the World Economic Forum found that about 85 percent of all food consumed in member countries of the GCC is imported. (The equivalent number in the United States is about 15 percent.) The Gulf’s dependency on imports rises to nearly 100 percent for rice and 90 percent for cereals. Some 70 percent of all food imports for those six countries pass through the strait, which connects the Persian Gulf with the Gulf of Oman and then the Arabian Sea.Iran’s throttling of traffic in the strait—one-fifth of the world’s oil supply runs through the roughly 20-mile-wide channel—already has driven oil above $100 a barrel, pushing up prices at the pump. But for the wealthy countries on the opposite bank of the strait from Iran, the bigger threat is a shortage of food and the soaring costs that could trigger.Governments are already tapping strategic food reserves and pivoting to alternative land and sea routes to try to ensure the food supply. The UAE’s strategic reserves of vital goods cover four to six months, the government has said, and it urged residents to report unjustified price increases (a.k.a. price gouging) through a dedicated hotline. Saudi Arabia has about four months of wheat supply after the state grains agency purchased nearly 1 million metric tons of wheat in January.Since the U.S. and Israel attacked Iran at the end of February, vessel traffic passing through the Strait of Hormuz is down at least 90 percent. On March 12, Lloyd’s List Intelligence, a maritime-analytics firm, recorded zero transits through the strait for the first time since the war began. Freight rates and war-risk premiums have surged. Even where cargo is still moving, delays can jeopardize food shipments.So far, Iran has not targeted food depots, so once shipments arrive they are safe (except for, of course, their proximity to military targets). But Iran could change tactics, depending on how the war unfolds. And how long the pressure on the strait might last is unclear. Even if President Trump were to declare the war over, Tehran may well see maintaining its campaign of harassment of ships in the strait as beneficial.[Read: Trump is learning that his bullying has consequences]As they wrestle with the prospect of shortages, the Gulf countries face an irony: They may not grow much of their own food, but they play an important role in helping other nations do so. The region provides nearly half of the world’s urea, a key ingredient in commonly used nitrogen-based fertilizers, and is a major producer of ammonia, sulfur, and phosphates. The shipping standstill in the strait has constrained those exports, pushing up global prices of some of these fertilizer components by about 25 percent. That’s a warning sign for global crop production.“We’re up for a food disaster and all we talk about is gas prices,” Michael Werz, a senior fellow at the Council on Foreign Relations who specializes in food security, told me. American farmers—already dealing with volatile commodity prices, high borrowing costs, and rising expenses—depend heavily on imported fertilizer. Spring planting accelerates in March and April, as does fertilizer demand. Any sustained disruption to supply chains from the Gulf could hit the U.S. heartland.Russia’s invasion of Ukraine in February 2022 caused worldwide anxiety about food security because the two countries supplied at least 30 percent of the world’s wheat, according to data from the Food and Agriculture Organization of the United Nations. Ukrainian ports were blockaded or threatened, mines dotted stretches of the Black Sea, and the country’s airports were closed to civilian flights. Silos brimmed with grain. Global wheat prices reached an all-time high the following month.Washington and Kyiv scrambled to come up with alternative ways to export Ukraine’s wheat, which was destined for the Middle East and Africa. Turkey and the United Nations brokered the Black Sea Grain Initiative, which allowed nearly 33 million tons of grain exports from three Ukrainian ports. Ukraine also moved grain by train and truck to its western borders and then to neighboring countries for further export.The supply crunch served as a reminder of both the fragility and the interconnectedness of the global food-supply network; countries that depend on imports for basics are at the mercy of events elsewhere in the world. And there isn’t much they can do about it. When crises happen, “countries make an attempt to become food self-sufficient, which is, they’ll turn inward and say, ‘Okay, we no longer want to rely on global markets for our food security,’” Caitlin Welsh, of the Center for Strategic and International Studies, told me. “But the thing is, very few countries around the world can actually produce the food that they need for domestic consumption.”The perils of food insecurity were all too clear to Middle Eastern leaders during the Arab Spring in 2010 and ’11, when mass protests toppled the governments of Tunisia and Egypt. Just before, global wheat production had been crippled by a series of climate disasters in major wheat-growing regions. A heat wave, drought, and wildfires destroyed about one-third of Russia’s harvest, prompting an export ban. Global prices surged by some 50 percent in 2010. The bread-subsidy program in Egypt, the world’s largest wheat importer, was pushed to the breaking point, propelling the protests.Gulf governments have expanded ports, built massive grain silos, and invested in high-tech farming such as hydroponics, vertical agriculture, and climate-controlled greenhouses to grow vegetables when the temperature outside routinely tops 110 degrees Fahrenheit. Saudi Arabia maintains millions of tons of grain-storage capacity and has poured tens of billions of dollars into agricultural initiatives and supply chains.But agriculture hasn’t met the need. Saudi Arabia largely abandoned its wheat self-sufficiency policies after depleting aquifers. Instead, sovereign wealth funds in the UAE and Saudi Arabia bought farmland and stakes in agribusiness abroad, including wheat in Eastern Europe, livestock in South America, and rice in South Asia.[Read: How much pain is Trump really willing to endure? ]But that, too, requires safe shipping. Some of the Gulf countries are better positioned to handle the strain. Saudi Arabia has a port on the Red Sea, an alternative route to get food in and oil and fertilizer out, Joseph Glauber, a fellow emeritus at the International Food Policy Research Institute, told me. “But you have problems in the Red Sea, too,” he added: Iran and its proxies have threatened to target U.S. ships there.Fresh water is also at risk. Iran has expanded its military targets to include water-desalination plants, the primary source of drinking water for millions in the Gulf. The countries of the Gulf Cooperation Council are among the most water-stressed globally, according to the World Resources Institute. On March 8, Bahrain’s Interior Ministry reported that an Iranian drone attack damaged a desalination plant. Kuwait’s government said fragments from an intercepted drone struck a fuel tank at the Doha West power and water station. Iran’s foreign minister, Abbas Araghchi, blamed the U.S. for an attack on one of its desalination plants on March 7, which he said had affected water supply to 30 villages; the Pentagon has denied responsibility.Decades before war threatened stockpiles and civilian infrastructure, the Gulf had begun to treat its oil as finite, a blessing that would one day be gone. Governments have turned to solar power and other forms of renewable energy to preserve the source of their wealth while preparing for the future. They tried similar long-term planning with food, buying up distant farmland and shipping its produce to state-of-the-art facilities at home.But agriculture has proved a tough proposition, leaving the countries exposed when war severed the supply chain. For all of its foresight, the Gulf now finds itself hanging on the simple question: When will the ships start moving?