Russia has to ready to undertake heavystrategic combing, in coordination with tactical airstrikes, and combined arms ground forces that mix infantry, artillery, and armour very well, if it is determined to recapture at least much of the lost territory... To me, even if Izium is not recaptured, it is necessary to recapture all of the territory within a couple dozen miles of Kupyansk. The Russians can do so if they are prepared to commit the resources to do so and if or when they recapture it all, they have to maintain a large garrison there for the duration of the war... Having a large force in Kupyansk at least keeps the Ukrainians wary of any major offensive to be relaunched further into Kharkov Region from that location... It also provides alternative means of supply to forces...
Quite frankly, it is strange that the Russian government is or was so blasé about the Kharkov Region and never decided to retain sufficient forces there in case of a major Ukrainian offensive or to itself threaten an offensive elsewhere in Kharkov or in the direction of Donbass... It has been established that the Russians were fully aware of the build up of the Ukrainians for weeks before the launched the offensive, but yet they did nothing in response to it quickly...
