The Russian government said on Saturday that it is suspending the operation of a United Nations-led safe passage scheme for Ukrainian grain in the Black Sea.

Moscow said it took the step after a Ukrainian drone attack on its warships earlier on Saturday at Sevastopol in Russian-occupied Crimea.

“The Russian side cannot guarantee the safety of civilian dry cargo ships participating in the ‘Black Sea Initiative’, and suspends its implementation from today for an indefinite period,” the Russian foreign ministry said in a statement on its website translated from Russian.