In the ruins of a tarred and dust-clouded apartment building amid constant shelling, a small group of Ukrainian soldiers find themselves face to face with a new type of Russian enemy: mercenaries, some of whom may be convicts sent to the front lines. The battle is both hot and critical around the city of Bakhmut. The Russian positions are within 200 meters of the Ukrainian military unit that CNN has joined. The unit is caught in a gruesome artillery duel, housed in basements, and uses commercially purchased drones as its best line of defense and intelligence. Through broken windows, through rooms full of rubble, Ukrainian soldiers look at the neighboring field, filled with countless blackened craters from artillery impacts. “They can see us here,” said a Ukrainian soldier, pointing into the distance. This is a new type of frontline fighter. Moscow’s manpower has dwindled after 80,000 casualties, according to US officials, prompting Moscow to turn to the country’s vast private mercenary sector, the Wagner Group. The Wagner group is reportedly run by the man known as “Putin’s chef”, Yevgeny Prigozhin. A man who matched Prigozhin’s appearance recently appeared on video in a Russian prison yard, extolling the virtues of his fellow prisoners to join Team Wagner and fight on the front lines. A Ukrainian drone operator is seen in the Ukrainian city of Bakhmut after a battle has recently escalated. (CNN) Here in Bakhmut is where this system is put into ruthless action. That city has been the focus of Russian forces in recent weeks, even as they abandon positions around Kharkiv and appear to be struggling to hold ground elsewhere. Wagner mercenaries have been deployed in this fight, according to several reports from Russian media, and have won around the eastern edges of the city. The mercenary attacks are often devastatingly fierce: Ukrainians tell CNN that Wagner fighters rush at them with small arms attacks, prompting the Ukrainians to fire back to protect their positions. The gunfire then retreats to where the Ukrainians are, allowing the Russian artillery to aim more accurately. Attacks are regular and shelling is almost continuous. read more