Sumy region, Ukraine – Vasyl was several miles deep in Russian territory when he heard the whizz of an approaching drone loaded with explosives. He had seconds to react. “It was very quick. We ran to the trees and then there was a bang a meter or two away from me,” the Ukrainian soldier said.

I look down and I see I have pieces of it in my leg. I don’t know what’s happening, so I put a tourniquet on and try to get out,” Vasyl  callsign Bumblebee told CNN in Sumy, the northern Ukrainian city where he is recovering from his injuries.

Kyiv launched its surprise incursion into Russia’s Kursk region last month, taking Moscow by surprise and quickly advancing some 30 kilometers 19 miles from the border. But the campaign slowed and, on Thursday, Ukraine’s President Volodymyr Zelensky confirmed that Russia had launched “counteroffensive actions.

The Russian Ministry of Defense said Russian forces had penetrated into the Kursk region, capturing 10 settlements. In the days leading up to this counter-attack, CNN spoke with 14 Ukrainian soldiers from five different units who were deployed to Kursk as part of the incursion. Four were wounded in the operation and are currently recovering in hospitals in Ukraine, while the other 10 are still conducting missions in Russia. They included infantrymen, members of a drone unit, armored vehicle drivers and sappers, or frontline combat engineers. Most have asked to remain anonymous or be identified by their first name and callsign only, given the sensitive nature of the topic and security concerns.

All 14 said the Kursk counteroffensive was a difficult operation with casualty rates on par with other parts of the frontlines. They said it was getting tougher, five weeks in, and some even questioned the decision to launch the incursion at a time when Ukraine was struggling to defend key towns and cities in the east of the country. It will get more and more difficult. There will be more artillery fire, more soldiers, and there will be very big and difficult battles, but we must do everything we can that improves our position  Ukraine wants peace, but peace when we win, not when we lose, Vasyl said. Russia is sending a lot of troops and artillery to Kursk We have a lot of guys who have been killed and we have a lot of destroyed hardware he added.  (CNN) …[+]