As the Commander of a Ukrainian Special Reconnaissance Unit, he fought in Ukraine’s surprise offensive in Kharkiv in the autumn of 2022, which pushed back an initial Russian invasion all the way back to the border.
But now Denys and his men are facing the prospect of doing the same all over again.
Russian forces have, in recent days, made small but significant gains right along the border in the Kharkiv region.
Their advances are only a few miles deep but have swallowed up around 100km (62 miles) of Ukrainian territory. In the more heavily defended east of Ukraine, it’s taken Russia months to achieve the same.
Russia claims its forces have now entered the border town of Vovchansk, which Ukraine disputes.