Russian Naval Staff intended to laying mines in the entrance to the harbours of Odessa and Novorossisk according to the Weekly Intelligence Summary Nr. 8 dated 28 August 1920

An item reported that the Russian Naval Staff informed the British S.N.O. at Sevastopol that the intention was to mine the entrance to the harbours of Odessa, Ukraine and Novorossisk, Russia as defence against an offensive of the Red Army. Ships were not allowed to proceed tho both harbours unless it was certain that the channels were clear to do so.

Source

The National Archives CAB 24-111-18