Russian drones struck Ukrainian grain facilities at the Danube River port of Izmail overnight in what a senior official said today was a systematic attempt by Moscow to prevent Kyiv from exporting grain to the world.

Deputy Prime Minister Oleksandr Kubrakov said the port’s export capacity had been reduced by 15% and that 13,000 metric tons of grain had been destroyed.

Grain facilities in the Odesa region on the Black Sea also came under fire in the eighth wave of attacks on Ukrainian port infrastructure since Russia quit a U.N.-brokered deal last month that had allowed Kyiv to ship its grain via the Black Sea.

The Danube River has become Ukraine’s main route for exporting grain since the collapse of the deal, which was meant to help tackle a global food crisis, and Izmail is Ukraine’s main inland port across the Danube from Romania.