Reuters reported that the Trump administration is considering lifting sanctions on some oil tankers, known as the “shadow fleet,” that have carried oil and petroleum products from sanctioned countries, including Iran, Russia and Venezuela.

A U.S. official said on Wednesday that the aim of the review is to reduce shipping costs, which have reached the highest level in history.

At the same time, the escalation of fighting between Saudi Arabia and Yemen’s Houthis and the resumption of attacks on ships in the region has supported oil prices.