In 2025, distillate (or diesel) fuel consumption (excluding biodiesel and renewable diesel) by the U.S. transportation sector was about 2.94 million barrels per day.
The U.S. alone uses 3 million barrels per day, 100 million barrels would last about a month. These barrels are not being released to the U.S. directly. It's going to help a little, but not much, and not for long.
My understanding is no country stocks significant reserves compared to what is used each day, because oil sitting in storage costs money instead of making profits. Instead, we produce what is used and can be sold as soon as possible. Essentially, Just In Time for the energy sector, like every other manufacturer. So, this isn't a real solution, it's just Trump trying to earn brownie points before the election.