The U.S. Strategic Petroleum Reserve, stored in underground salt caverns in Texas and Louisiana, has fallen to its lowest levels since 1983. These reserves are designed to blunt the impact of oil shocks such as the Iran War.

In May, President Trump said the U.S. would release up to 172 million barrels to help tamp down prices during one of the world's worst energy disruptions. The war with Iran hinges in large part on control of the Strait of Hormuz, through which about 20% of the world's oil transited before the conflict.

David Uberti explains how the reserve works and the debate over what's next for the U.S.'s strategic oil reserves. The drawdown raises questions about energy security and future replenishment efforts.