Kerch

After its annexation in 2014 Putin sought to cement Russia's control over Crimea, first with a 12-mile bridge built over the Kerch Strait in 2018 and then by capturing a land bridge along the Sea of Azov coast in 2022.

Satellite images reviewed by BBC Verify have shown a major oil slick spreading across the Kerch Strait that separates Russia from annexed Crimea, a month after two oil tankers were badly damaged in the Black Sea.

"In general, Russia has suffered more than any other country so far from the Kerch Strait accident," Dmitry Markin of Greenpeace said.

The incident took place in the Kerch Strait, which separates Russia from the occupied Crimean peninsula.

Kyiv has launched multiple attacks and attempted attacks on the Kerch Bridge since Moscow began its military offensive.