On the morning of 16 March, Ukrainian drones struck multiple refineries in the Samara region of Russia, For more than a week, Ukrainian drones have targeted Russian oil infrastructure, particularly refineries. If the attacks become regular and continue indefinitely, they will impose significant costs on the Russian economy and military.

Ukraine is presenting Russia with the same air defence dilemma that Kyiv currently faces. Russia uses missiles and Shahed drones to attack Ukrainian cities. Ukraine has to keep a massive amount of its air defence behind the frontlines. Doing so offers the Russian air force slightly more safety in the air and diverts international focus from providing Ukraine with offensive systems. A large amount of foreign military aid to Ukraine has been aimed solely at defending cities far from the bulk of the fighting.

Since oil facilities tend to be large, undefended, and flammable, they make an ideal target for Ukraine’s OWA drones

The major difference is that Russia’s oil dependency means that strikes on refineries will have an outsized impact on their economy. Oil money makes up a plurality of Russia’s federal revenue and is a major bargaining chip in its relations with countries like India. While it’s unlikely that Ukrainian drones can force a permanent shortage of oil or petroleum, constant disruptions can produce immediate financial costs. Saudi Arabia learned this lesson in 2019, when strikes temporarily reduced their ability to refine oil in a matter of minutes.

The key to Ukraine’s campaign is getting a significant number of cheap one way attack (OWA) drones. These drones aren’t impressive on their own: their engines, navigation, and payload are usually far inferior to a traditional missile. However, using less advanced components is cheaper and makes them easier to manufacture without an advanced missile industry. Since drones in general are a major focus of the Ukrainian war effort and most of Ukraine’s partners refused to provide long range systems for much of the conflict, OWA drones capable of striking deep into Russia were an inevitable innovation.

Since oil facilities tend to be large, undefended, and flammable, they make an ideal target for Ukraine’s OWA drones. Unlike many military targets like parked vehicles, oil infrastructure never moves. Ukraine’s drones have smaller explosive charges than a traditional missiles but are still able to cause serious damage. With a lower cost per unit than a missile, Ukraine can afford to send multiple drones at once to increase the odds that one makes it through.

The threat is impossible for Russia to ignore, but potentially dangerous for them to address. The obvious solution is to provide refineries with air defence systems. However, Russia has a limited number of these, so the choice is to reduce coverage at the frontline, reduce protection of major cities like Moscow that have been targeted in the past, or reduce protection along its borders with European countries. None of these options are desirable. Worse still, a facility with a single air defence system may not be able to intercept multiple Ukrainian drones.

The unknown factor is how many OWA drones Ukraine has and how fast they can make them. Previous OWA drone campaigns, like the high profile attacks on Moscow midway through last year forced Russia to start bulking up air defence in major cities, were short lived and used fewer drones than Moscow’s attacks on Ukrainian cities. If the Ukrainian military can’t maintain a consistent tempo of strikes, it will reduce the impact of the campaign and give Russia more time to look for solutions.

Some of Ukraine’s partners, like the US, are reportedly unhappy with the strikes, but they can and should support Ukraine’s OWA drone production. On 7 March, the UK government announced that they would supply 10,000 drones to Ukraine, though they did not specify the types or model. Even more countries not comfortable delivering completed drones, they can provide consistent access to components like engines or navigational systems. Most OWA drones rely on small internal combustion engines, something nearly every country has access to. If Ukraine can produce enough drones to threaten Russia indefinitely, then the Kremlin will have to shoulder yet another set of financial costs and military humiliations.