The “Military Informant” Telegram channel complained that the defenseless manner in which the tankers had travelled had become in effect a shooting gallery for Ukrainian drone operators, with no cover from a Black Sea Fleet, which could nowadays barely defend itself.

Mikhail Zvinchuk, author of the Telegram channel “Rybar” pointed out that the Black Sea Fleet had “now shut itself in at Novorossiysk”.

These strikes will come as painful blow given declining oil refining capacity and fuel shortages, in Crimea especially.

In late June, Vladimir Putin estimated Crimea’s monthly fuel needs at 70,000 tons and promised to secure supplies to the peninsula by increasing deliveries by both land and sea. The tankers attacked in the Sea of Azov may well have been carrying considerably more than that.

There is now fuel rationing or shortages in more than 90% of Russian regions, and Russia has now banned exports of diesel. Queues are reported at filling stations in the biggest cities.

In Crimea, Russian-appointed authorities are struggling to cope with disruptions to power supplies and transport.

Ukraine’s military has already jeopardised Russia’s land supply routes to the peninsula, and they are now firing on its sea routes as well.

Additional reporting for BBC Verify by Alex Murray, Adam Durbin, Kevin Nguyen and Tom Shiel