Last week’s massive Russian attacks on energy infrastructure in the Poltava and Kharkiv regions in Ukraine have forced the shutdown of about 60% of the Ukrainian natural gas production, sources familiar with Ukraine’s talks with its allies told Bloomberg. With more than half of its domestic gas production offline ahead of the winter, Ukraine will be forced to spend a lot more on natural gas imports to meet winter heating and power demand. “Russia will do everything to prevent us from extracting our gas,” Ukraine’s…