“It is a humanitarian catastrophe. The military that were involved in active hostilities here are completely surrounded. There are supply problems with water, food, medication and general supply. It’s a very difficult situation,” said Serhiy Volyna, deputy commander of the Marine Battalion in Mariupol, who has been fighting in the region since 2014, when Russia annexed Crimea.

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“We have been encircled in Mariupol for more than 40 days. The enemy outnumbers us and in terms of weaponry, their artillery, they have sea-based artillery, tanks, armored vehicles and of course mortars. It is difficult for us,” Volyna said.

It's just air bombardment… They are just wiping the city off the face of the Earth and wherever any reinforcements they are also using their tanks to crush that, he continued.

Volyna served with Ukrainian forces during the Crimean annexation of 2014 and also served with Ukrainian forces and took part in military operations in the Donetsk and Luhansk regions, now partially controlled by Russian backed separatists.

When asked if he may now be fighting against former colleagues who crossed over to the Russian side, he replied: “Yes, of course it is entirely possible.”

He called it a “strange situation” that former members or the Ukrainian marines and the Coast Guard of the Black Sea Fleet are “now fighting” in Russian units, labelling them “enemies of our country.”

“Whenever they approach us, they suffer huge losses. That's why after this, having suffered the initial defeat, their marines are demoralized so they're trying to enter a city only when it's destroyed,” he added.