Russian forces struck a grain terminal in the southern Ukrainian city of Kherson, Ukrainian officials said on Saturday, extending a bombardment of the country’s infrastructure that has raised alarm about Kyiv’s ability to ship grain to the world.

President Volodymyr Zelenskyy of Ukraine has vowed to enhance air defenses around the port and the southern coast, but Kyiv’s resources are stretched thin and it faces difficult choices about where to deploy the limited number of air defense systems that can shoot down Russia’s most sophisticated missiles.

Ukraine continues to ask its Western allies to speed up the delivery of more air defense systems and warn that continued Russian bombardment could leave it without the necessary infrastructure to ship grain even if Black Sea shipping lanes reopen. Moscow has struck Ukrainian ports nearly daily since pulling out of a deal last week that allowed Ukraine to ship its grain despite the war.