Just as important, however, is Iran’s location. Unlike Iraq, Iran is a maritime power bordered by the Caspian sea to the north and the Persian Gulf and the Gulf of Oman to the south. It shares land borders with several troubled U.S. allies, including Afghanistan, Pakistan, Turkey and Iraq.

Its location in the center of Eurasia is particularly important for trade. About a third of the world’s oil tanker traffic passes through the Strait of Hormuz, which is bordered by Iran and Oman. At its narrowest point, this shipping route is just under two miles wide. Blocking it could lead shipments of daily global oil exports to drop by an estimated 30 percent…

Iran’s navy has a real advantage against the United States, too. It doesn’t need big ships or firepower to block off the Strait of Hormuz, for example, but could use mines or submarines to force a halt in trade.

U.S. war games have suggested that speedboat suicide attacks and missiles could be surprisingly effective against the American military. A 2017 report from the Office of Naval Intelligence found that the navy of the Revolutionary Guard, which is distinct from Iran’s regular navy and focuses on smaller and faster but still heavily armed vessels, had received more responsibilities to protect the Persian Gulf.