As Ukraine started a swift counteroffensive operation across the line, Britain estimates that Russia appears to have lost at least four fighter jets in the last ten days.

Russia may have lost at least four fighter jets in Ukraine in the previous 10 days, according to a statement released by the British Ministry of Defense on September 19. British records suggest that since Moscow began a military campaign in the neighbouring country on February 24, Russia may have lost a total of 55 warplanes.
The Russian Air Force may have increased risks in order to give close-range assistance to Moscow’s ground forces, according to the UK, which said that this may be a contributing factor in the increased Russian losses. According to the UK Ministry of Defense, Russia may have felt pressured to follow Ukraine’s lead in the counteroffensive operation.
As the demarcation lines between the two sides have been shifting rapidly lately, British intelligence also suspects that some Russian pilots may have inadvertently flown into Ukrainian airspace and became lost in a region where Kiev air defence had deployed more heavily.
In recent weeks, Ukraine has engaged in a swift counteroffensive campaign in the Kharkov region of the northeast, taking back many significant cities. Ukraine claims it diverted Russia’s attention by announcing a counterattack in the south, but afterwards switched its attack to the northeast, where Russia had placed relatively few forces.
On September 10, the Russian Defense Ministry stated that troops had been withdrawn from various locations in the Kharkov province of northeastern Ukraine, including the city of Izyum, in order to redeploy and concentrate on the Donetsk operation. This entails Kiev regaining control of key strategic areas, which Russia views as a base of operations for its forces in eastern Ukraine.
According to military experts, Russia decided to evacuate its forces in order to reduce fatalities in the wake of the Ukrainian army’s fierce counterattack in Kharkov. According to experts, Russia will soon mobilise its forces in preparation for a significant counterattack.