How much exactly is hard to say, though the potential to remove a fifth of the world’s oil could cause a severe spike. Talmadge noted in a 2008 paper that the Iraqi invasion of Kuwait in the 1990s, which stopped oil exports from both countries, doubled the price of oil at the time and kept them elevated for a year. Today these effects would be mitigated somewhat by strategic oil reserves that can make up supply shortfalls for months.
History suggests that the U.S. need not clear a potential minefield in the strait alone. During Operation Candid Hammer in 1991, which Talmadge describes in the paper, a coalition of U.S., British, French, and Belgian ships cleared almost 1,000 Iraqi mines from off the coast of Kuwait over the course of nearly two months.
An operation in the Strait of Hormuz would be more complicated, because Iranian coastal defenses would likely be firing at the ships doing the clearing operations. So even though allied countries could participate in mine-clearing, the U.S. would likely take the lead in bombing Iranian missile batteries, perhaps with help from allies, such as France and Britain, that have advanced air forces. Talmadge estimates such an operation could take anywhere from days to weeks.
“It’s arguably still in our economic interests to protect Gulf oil,” Charles Glaser, the director of the Institute for Security and Conflict Studies at George Washington University’s Elliott School of International Affairs, told me. “It would be better if other countries were militarily able to do that—frankly most of them are not in a situation where they can … If we don’t do it, it’s quite unclear that anyone will fill the gap.”
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Glaser pointed out that for the present, Gulf oil is very much still flowing. “It’s not interrupted, there’s been a small risk … It’s very, very hard to significantly close the flow of oil through the Gulf. And so far, that’s not happening at all.”
So does the risk require a massive forward U.S. presence in the Gulf? “We had far, far fewer military assets in the region during the Cold War—mostly naval—and we were still able to protect the flow of energy,” Emma Ashford, a research fellow in defense and foreign policy at the libertarian Cato Institute, wrote in an email. “To be frank, our troops in the region have been more destabilizing than stabilizing for energy markets in recent years: invading Iraq, toppling [Muammar] Gaddafi in Libya, etc. We could protect the flow of energy supplies with far, far lower levels of military presence than we have today.”
Meanwhile, Secretary of State Mike Pompeo is in the region trying to stitch together a coalition to protect Gulf energy security, though the parameters of what such a coalition will do are unclear. As Paul McLeary of Breaking Defense points out, the U.S. already oversees a coalition of 33 countries who help monitor threats to shipping.
“There are moral hazard dynamics going on,” Talmadge said. “The United States has not been willing to walk away from the Gulf, so other allies may not step up to do anything because they know that if they don’t, the U.S. will.”