Russian air defences have shot down one of the country’s most advanced fighter jets in a friendly fire incident, according to reports.
A Russian Telegram channel with close links to the country’s air force appeared to confirm the incident on Friday when it paid tribute to the pilot, who did not survive.
Footage showing a fireball falling out of the sky began circulating on Friday.
Ukrainian channels claimed that a Russian S-300 missile had brought down the aircraft, which is believed to cost more than £35 million.
The Su-35 was designed to “significantly increase engagement effectiveness against air, land and sea targets”, according to the United Aircraft Corporation, a Russian aerospace and defence corporation.
Experts say that the plane was made to fight back against Western aircraft such as the Lockheed Martin-made F-16.
Tokmak, which was captured by Russian forces early in the war, is situated on the road to the occupied city of Melitopol.
Ukraine’s counter-offensive is working to push through Russia’s defences on the road to Tokmak, then on to Melitopol before reaching the Sea of Azov.
According to the Institute of War, Russia’s 70th and 71st Motorized Rifle Regiments are fighting between the current frontline in Zaporizhzhia and Tokmak.
Seizing Tokmak would represent a huge victory for Ukraine’s forces, Gen Oleksandr Tarnavsky, who is leading Ukraine’s counter-offensive along the southern front line, told CNN last week.
“Tokmak is the minimum goal … The overall objective is to get to our state borders,” he said.
Western analysts have said that Russia’s air force has an unusual toll of self-inflicted losses.
They believe that it is the result of a push to complete training quickly, the pressure of combat and a lack of experienced pilots.
Russia has lost four Su-35 jets since Vladimir Putin’s forces invaded Ukraine in February last year, according to the Dutch open-source intelligence outlet Oryx.
Russia has also experienced self-inflicted losses on the ground.
Earlier this month, more than 60 Russian soldiers were thought to have been killed or wounded by friendly fire as they made a hasty retreat from the village of Opytne, in the Donetsk region.
The chaotic withdrawal was mistaken for a rapid Ukrainian advance across an open field by a Russian drone operator, who ordered an artillery strike.