On Friday night, Russia carried out its most extensive air attack since the war began. One theory is that the attack is a response to Ukraine destroying a Russian ship a few days ago.
The attack at the port of Feodosia has caused Russian security services to work feverishly in the area, says Jörgen Elfving, military analyst specializing in Russia. The powerful explosion indicates that the ship was loaded with explosives of some kind.
"According to some sources, there have been drones and artillery ammunition on board and that it has given rise to the big explosion," he said.
According to Jörgen Elfving, the question now is whether it was a pure stroke of luck or whether Ukraine had information about the ship's cargo and deliberately selected it as a target.
Looking for informants
Something that indicates that Ukraine had the information is information that Russia is now intensively looking for informers.
"The Russian security service is now turning the whole of Feodosia upside down in search of possible information to the Ukrainian side," says Elfving.
According to him, it does not have to be someone on the Russian side, but it may be enough that someone with binoculars has been able to observe the ship and the cargo.
"There is a relatively active Ukrainian resistance movement in Crimea that gathers intelligence for the Ukrainian armed forces.
Do you think they search among Russians as well?
"Considering what I know about the Russian security services, I don't think they will leave no stone unturned.
According to data from the UK's Ministry of Defence, 20% of Russia's Black Sea Fleet has now been knocked out by Ukraine. Hear why it's so important for Ukraine to attack the Russian navy in the video above.