Bangladesh, Aug. 15 -- The US Strategic Petroleum Reserve (SPR) has fallen to its lowest level in more than four decades, and the timing could hardly be worse, from an American perspective. Last week the stockpile dropped by another 6.1 million barrels to 298.7 million, the first time it has fallen below the 300 million mark since 1983.

The United States began the year with roughly 415 million barrels. The Trump administration has since released large volumes to soften the shock from the ongoing war with Iran, including an order in March for 172 million barrels while Tehran has restricted oil exports through the Strait of Hormuz.

The emergency buffer itself is now being drawn down while the emergency continues. The SPR was built precise...