Ukrainian drone strikes have forced Russia to completely halt shipping in the Sea of Azov in less than a week—showing once again how a country without traditional naval power can still effectively blockade maritime corridors.

Ukraine’s Unmanned Systems Forces have flown one-way attack drones to target and strike more than 100 Russian tankers and other ships every night between July 6 and July 13, along with posting video evidence showing such drone strikes. The campaign has forced Russia to completely shut down the shipping route that flows from Russia’s Don River into the Sea of Azov, and to halt all Kerch Strait shipping transits from the Sea of Azov into the Black Sea, according to Reuters reporting.

The shutdown of such maritime lanes has further isolated the Russian-occupied Crimean Peninsula by cutting off seaborne delivery of fuel in particular. Crimea had already been experiencing severe fuel rationing and power outages as Ukraine stepped up its mid- and long-range drone strike campaign on Russian energy infrastructure and supply lines, leaving behind damaged oil refineries with billowing black smoke and burned-out trucks littering highways.

Restrictions on shipping in and out of the Sea of Azov could also impact one-quarter of Russian grain exports, Reuters reported. Wheat prices have started rising because Russia is the world’s largest exporter of grains.

“Ukrainian strikes against Russian seaborne gasoline transports over the past week represent a new phase in Ukraine’s efforts to isolate occupied Crimea from the Russian logistics network and to disrupt Russian seaborne shipping routes, especially for petroleum products and grain,” according to the Institute for the Study of War, a think tank based in Washington, DC.

The Ukrainian videos showing the strikes from the drones’ perspective typically cut off at the moment of impact. But burning ships are visible in some videos taken of the aftermath and can also be seen in public satellite imagery from the European Union’s Copernicus Sentinel satellites and other sources.