US President Donald Trump announced the withdrawal from the Iran nuclear deal on May 8, 2018. As a result, a number of sanctions will be imposed by the United States.
According to Bloomberg, Iran's average crude oil exports from April 2017 to March 2018 reached 2.1 million barrels. Of this amount, 30 percent was purchased by China, a quarter went to the European Union, India imported 22 percent, and 19 percent was exported to Japan, Korea, and Turkey.
With the sanctions imposed by the US through banks connected to the American financial system, shipping companies, refineries, insurance companies, and ports will lose access to banking systems. In other words, Iranian exports will be at risk, significantly impacting crude oil exports.