Flag of Eswatini. Manuel Augusto Moreno/Getty Images

Dozens of tankers remain stuck doing nothing months after being sanctioned by the Treasury Department — a signal of the US’s scope to disrupt Moscow’s petroleum supply chain if it chooses to.

Since October, 40 ships involved in Russia’s oil trade have been added to the Treasury’s list of designated entities, mostly for breaching a price cap that’s meant to restrict the Kremlin’s access to petrodollars.

Only one of them, the SCF Primorye, collected a cargo since being designated. It is heading to Asia. if it’s able to offload the barrels it’s carrying without any problems, it might encourage Russia to use more of the ships again.

The sanctions and price cap that have been imposed on Russia have been criticised for being too easy for Moscow to work around, given how large the country’s crude flows have remained. However, the inactivity of the fleet shows that when measures are taken against individual vessels, they can be effective.

Twenty-one of of the 40 belong to Russia’s state-controlled shipping company, Sovcomflot PJSC. Most of the other 19 are controlled by United Arab Emirates-based Hennesea Holdings.

The sanctioned ships make up a small fraction of the shadow fleet of vessels that’s been built up with the help of proxy companies to get around the G7’s restrictions on shipping services.

One of the 40, the Turkish-owned Yasa Golden Bosphorus, was removed from the list in April, allowing it to benefit from international standard services, such as insurance. Since being de-listed, the ship has loaded a cargo of US crude, but remains anchored off the Texas coast.

The rest of the sanctioned ships are sitting idle and empty, dotted around the world, according to vessel tracking data compiled by Bloomberg.

Eight of the Sovcomflot tankers, are off Russia’s Pacific Ocean ports of Vladivostok and Nakhodka, where some have been for as many as five months. One that was anchored there has headed empty back toward the Suez Canal and another has been taken to a maintenance dock in China.

There’s a second congregation of idle, sanctioned Sovcomflot tankers in the Black Sea.

Shortly after arriving, each of them appears to have switched off transponders revealing to digital tracking systems where they are. However, given that the vessels would need to provide signals if they sail through Turkey’s narrow Bosphorus shipping strait to leave the Black Sea, all of them are almost certainly still in the area.

The first of the seven-strong flotilla arrived in December. The most recent got there earlier this month after delivering a final cargo of crude to China, which it had loaded at the Pacific port of Kozmino just days before being sanctioned in February.

The other three of the company’s sanctioned ships are in the Baltic. Two are anchored outside the export terminal at Ust-Luga. The other is further west, off the coast of Estonia, where it’s been since late February.

The 18 sanctioned Hennesea tankers also appear to have been idle since most of them were added to the Treasury’s list in January — one had already been named the previous month. Like their Sovcomflot counterparts, the vessels have congregated in a small number of locations.

Ten are off the coasts of China and South Korea, including two that are at maintenance docks.

Most of the rest are off Port Said in the eastern Mediterranean where some have been for more than three months.

Signal spoofing, where tracking systems receive an incorrect location signal, has briefly put several of these ships at various regional airports. The Sensus, for example, shows up at on the taxiway of Beirut’s Rafic Hariri airport in Lebanon on May 17. Other recent signals have also put ships at Cairo airport.

The only one of the sanctioned Hennesea tankers that appears that it may be active is the LR2 tanker Apus. It left Port Said in late March, arriving in the Persian Gulf in mid-April. It then spent several days moving at speeds of less than 1 knot near Iran’s Soroosh oil field, before heading to Khor Fakkan in the UAE, where it was last seen at the end of April.

In a separate development, at least 10 of Sovcomflot’s sanctioned tankers have been renamed and reflagged to Russia.

The data show five of the Hennesea tankers are also operating with new identities, all of them now sailing under the flag of Eswatini. The tiny land-locked country in southern Africa, formerly known as Swaziland, is among the latest to offer ship registry services.

This comes after the International Maritime Organisation (IMO) issued a warning in April regarding flags it identified as fraudulent. It raised specific concerns over flags purportedly administered on behalf of Guyana and Eswatini respectively.

Tanker names are often changed after being sanctioned in order to distance the vessels from listings on sanctions databases. They remain traceable by unique numeric identifiers assigned to them that don’t change.

*This article has been updated by News24 to note the IMO’s April statement.