By Max Hunder KYIV (Reuters) -Ukraine said on Tuesday it feared Russia would step up attacks on its energy system to turn the screws on Kyiv this winter, and that it was pleading with Western powers for air defence technology to avert this. A series of devastating strikes hit Ukraine’s power and heating infrastructure over the last two days, causing mass blackouts across several eastern regions. “We expect the quantity of such attacks to grow, and are ready for various scenarios,” senior presidential adviser Mykhailo Podolyak told Reuters. Podolyak added that Ukrainians should be prepared for …