Ukraine is facing a very worrying two to three months as winter approaches, with Russia continuing and intensifying air strikes on energy infrastructure. Samir Puri, a visiting lecturer in War Studies at King's College London, told Al Jazeera that the Kremlin's most credible military option is to collapse Ukraine's energy grid, as its ground war has ground to a halt in the Donbas. He warned that Vladimir Putin will have been encouraged by last winter's progress and may "go for broke" in trying to plunge Ukraine into a humanitarian catastrophe. Puri said Ukraine's Achilles' heel is its chronic lack of air defence, with Patriot interceptors almost spent and Russia now deploying jet-powered drones. On diplomacy, Puri said Russia is "fighting and talking at the same time", maintaining diplomatic channels while still pursuing military goals. He said Moscow has not been dissuaded from trying to take the last 20 per cent of the Donetsk region, leaving Ukraine facing a particularly difficult period ahead. Subscribe to our channel: http://bit.ly/AJSubscribe Follow us on X: https://X.com/AJEnglish Find us on Facebook: https://www.facebook.com/aljazeera Check our website: http://www.aljazeera.com/ Check out our Instagram page: https://www.instagram.com/aljazeeraenglish/ Download AJE Mobile App: https://aje.news/AJEMobile #UkraineWar #Russia #Ukraine #Putin #Zelenskyy #UkraineEnergy #UkraineEnergyGrid #RussianAttacks #RussiaUkraineCeasefire #RussiaUkraineStalemate #AlJazeeraEnglish