U.S. penalties on shippers transporting Russian oil in breach of the G7's price cap could push more Russian cargoes onto vessels referred to as the ghost fleet and away from mainstream tankers, shipping sources and analysts told Reuters. It was designed to keep oil flowing to markets while reducing Russia's energy earnings that it can use to finance its war on Ukraine, but it has created a two-tier global shipping market. One tier relies on vessels known as the ghost fleet that are past their traditional lifespans, meaning they are at greater risk of leaks and spills.