The U.S. Strategic Petroleum Reserve played a critical role in keeping a lid on oil and gasoline prices during the Iran war, but it's running low.

The US Strategic Petroleum Reserve has dropped to 349.2 million barrels, a 43-year low, as Trump drains reserves to fight gas prices amid the Iran crisis.

The reserve was created in 1975 in the wake of the Arab oil embargo, with the intention of protecting the markets and consumers from severe supply shocks.