A supertanker called Happiness is carrying 2m barrels of trouble for Iran. The crude vessel filled up at a terminal operated by Iran’s national oil company on Kharg Island at the start of this month, before setting off on a journey for Asia, according to ship-tracking data. But it was sailing into a global market where Iranian oil is acquiring pariah status. When Happiness I — its official name — exited the Strait of Hormuz the tanker turned off the system that allows traders to track its movements.

As the US prepares to reimpose sanctions on Tehran’s energy sector in November, the vessel joins a fleet of ghost ships that symbolizes the pressure growing on Iran to hide the identity of its buyers. Following President Donald Trump’s withdrawal from a nuclear deal Iran signed with world powers, he is seeking to cripple the Iranian economy with sanctions that impose severe financial penalties on any party involved in trading its crude. Iran cannot easily abandon the lucrative export business that generates much-needed government revenues.

There are growing signs of the country reverting to an old playbook of selling in secret. Happiness I is one of at least seven tankers carrying Iranian oil that are no longer broadcasting their position. The tanker “has not sent a signal since” turning off its transponder on September 16, said Matt Smith, director of commodity research at ClipperData, which is tracking the vessels filled with Iranian oil.