The commanders of two Ukrainian units defending the besieged port city of Mariupol issued a video statement saying they had managed to join forces as Russia claimed to have advanced on the city. Their statement comes as Ukrainian forces remain stranded inside Mariupol, which has been under weeks of relentless bombing. The Russian military has repeatedly claimed to have taken strategic positions in the city, but has also faced fierce resistance from Ukrainian forces. Denis Prokopenko, the commander of the Azov Regiment, said his unit had been linked to troops of the 36th Marine Brigade, but acknowledged that some Ukrainian defenders had surrendered. “These are real men [of the 36th] who have chosen the path of war “, he said and” Do not make heroes from deserters and fighters who surrendered voluntarily. They have chosen the path of shame and in no case should they be heroized “. “We know what we are doing, because we are here. We will do whatever it takes to successfully complete our mission,” said Serhii Volyna, commander of the Marine Brigade. Ukraine’s presidential adviser Oleksiy Arestovych said earlier on Wednesday that after a “risky maneuver” the last defenders of the besieged port city of Mariupol were able to join forces. “This happens when the officers do not lose their heads, but maintain firm command and control of the troops,” Arestovic said. CNN can not independently confirm the details of the operation. Meanwhile, in a statement Wednesday, Russian Defense Ministry spokesman Lt. Gen. Igor Konashenkov said the commercial port of Mariupol had been captured. CNN could not independently verify this claim.