Ukraine appears to be attacking Russia's oil-and-gas industry with small, cheap drones that can bypass its air defenses

• Oil and gas facilities in Russia have caught fire in recent weeks following suspected drone attacks.
• In the latest attack, an oil refinery in the southwestern Volgograd region was ablaze on Saturday.
• Russia's air-defense systems have proven to be less effective against small drones.

Ukraine appears to be targeting Russia's oil and gas industry with small, cheap drones as it seeks to disrupt Russian supply lines.