Ukraine’s drone strikes are hitting where it hurts most: Russia’s oil sector, dragging crude output to a one-year low and squeezing Kremlin revenues.

Russia's crude oil output fell to 8.8 million bpd in April, down 460,000 bpd year-on-year as Ukrainian drone strikes disabled over 10% of refining capacity.

Russia's oil production has declined for a sixth consecutive month, with escalating Ukrainian drone attacks on the country's energy infrastructure contributing to the downturn by…