When a ship stock in the middle of ocean due to out of fuel how do they get fuel?

First the owners and the captain make sure they have plenty of fuel to make the trip or plan to stop in a certan port to refuel. U.S. Navel Ships, those who still use fuel oil are required to keep a certain percentage of fuel oil on board at all times. But if a ship does run out of fuel oil they would have to call some port and request an oil tanker to bring them more fuel.