On Sunday Russia's defense ministry announced its forces launched a successful UAV attack on an oil depot that's near the Romanian border. It was reportedly destroyed, but was seen as vital to supplying Ukrainian forces deployed in the Odessa region.

"The Russian Aerospace Force made a group strike by unmanned aerial vehicles this night against fuel storages used for supplies to military vehicles of the Ukrainian Armed Forces in the port of Reni, Odessa Region. The strike objective was achieved. All the designated targets were engaged," the ministry said.

The statement continued: "Tactical and army aviation, rocket troops and artillery of battlegroups of the Russian Federation Armed Forces engaged manpower and materiel of the adversary in 119 areas."

The main oil depot that was hit is located on the bank of the Danube River which lies opposite NATO-member Romania, raising tensions given Romania has been key to setting up an alternative grain export route for Kiev.

Additionally, more military and infrastructure facilities were hit particularly connected to Ukrainian ports.