Iran's threat to close the Strait of Hormuz has triggered alarm about the flow of oil from the Persian Gulf, but for the arid, oil-rich countries in the region it poses another uncomfortable question: For how long can they feed their people if the strategic waterway is blocked?

Saudi Arabia, Kuwait, Qatar, and the United Arab Emirates are among the world's richest countries, but as much as 90% of food needs for these mostly desert nations is brought in from abroad, according to the Royal United Services Institute, a British think tank.

Much of those imports come to the Persian Gulf via the narrow Strait of Hormuz. Iran has threatened to block the strategic waterway—through which about 35% of the world's ship-borne oil is exported, in the opposite direction—in response to sanctions over its nuclear program. It remains uncertain whether Iran could succeed in closing off the shipping lanes, and the U.S. and its allies are taking measures to make sure that doesn't happen, including preparations to de-mine the strait.

But any prolonged closure of the strait could lead to food shortages in the Persian Gulf and force countries to find alternate channels.

As a result, the Gulf countries have been dusting off plans to improve their food security, and are investing in what amount to insurance policies against the effects of a broader conflict.

"One of the key worst-case scenarios revolves around the Strait of Hormuz," said David Roberts, the deputy director and a research fellow at the Royal United Services Institute.

The strategy, analysts say, is to multiply sources of food, water and energy in case one or more sources are cut off in the wake of a conflict.

Such efforts have long been in play. The U.A.E. has even considered a plan to bring in fresh glacial runoff from Patagonia in Chile in gigantic bags that would be dragged across the ocean. The bags have yet to be fully tested and the proposal is still in the exploratory stages, but the plan—and the audacity of its scale—illustrates the lengths to which the Gulf countries are willing to go to slake their thirst for resource security. A group of government officials and businessmen from the U.A.E. traveled to Chile to inspect the glacier two years ago.

Such planning has been accelerated since Iran aired threats in January to close the strait in response to the approval of sanctions by the U.S. and Europe targeting Tehran's oil revenue.

This year, Qatar said it would spend nearly $ 3 billion on reservoirs to store enough water to last a week, giving the country a strategic reserve. Qatar estimates it has one of the world's highest per capita water use rates.

In March, two companies owned by the Abu Dhabi government in the U.A.E. said they would build a terminal to import the liquefied natural gas it uses to produce electricity and power its water desalination plants. The terminal—for imports through Fujairah, a city that lies on a small strip of coastline outside the Strait of Hormuz—would prepare the U.A.E. for any interruption of supply from Qatar, from which the it gets most of its natural gas.

Other resource-security investments in the U.A.E. in recent years include the construction of a grain terminal in Fujairah and purchases of farmland overseas. Abu Dhabi is developing 70,000 acres of farms in Sudan, while Qatar and Saudi Arabia have bought farmland as far afield as Argentina and Ukraine.

"This is a psychological issue as much as physical one," said Mustafa Alani, a security expert at the Geneva-based Gulf Research Center. "You need to feel you're not going to be held hostage."

Water is perhaps the most complex of the region's resource-security puzzles. Gulf countries have some of the lowest rainfall rates and smallest water resources in the world. Gulf countries satisfy demand by desalinating seawater, but that leaves them vulnerable if their desalination plants malfunction or are attacked.

As the first Gulf War ended in 1991, Saddam Hussein's forces targeted Kuwait's desalination plants in desperation, damaging its supply.

Storage projects such as Qatar's reservoirs are one way countries are trying to address the issue. Abu Dhabi has also looked at pumping desalinated water into an underground aquifer outside the city.

Gulf governments have discussed a regional network of pipes linking desalination plants, but cost and politics have so far made it unfeasible.

Meanwhile, efforts to grow food domestically have largely been abandoned in the Gulf because of the demand they placed on limited water resources.

As populations of the Gulf nations grow, food demand is expected to increase. Dubai imported $ 6.7 billion in food and beverages last year, according to official figures, up from $ 3.85 billion in 2005, including large imports of wheat and grains.

The U.A.E. as a whole imported 1.3 million tons of wheat in 2009, more than double what it imported in the mid-1990s, according to the United Nations Food and Agriculture Organization. The U.A.E.'s population has grown to 7.9 million last year, according to the World Bank, from about 2.3 million in 1995.