By Anna Voitenko
ZAPORIZHZHIA REGION, Ukraine (Reuters) - Three Ukrainian soldiers draw back the sliding roof of their dugout near the frontline, quickly launch several mortar bombs and shout: "Presents for the Russians!"
To avoid revealing their position, they rapidly replace the makeshift roof -- consisting of branches and leaves covering tarpaulin stretched over a metal frame -- and take cover.
It's a routine they repeat frequently as Ukraine's army tries to battle through vast Russian minefields and heavily fortified trenches in the southern region of Zaporizhzhia.
Kyiv says its troops are gradually pushing back Russian forces in the south after 18 months of occupation, but that fighting is heavy three months into the counteroffensive.
"The Russians resist fiercely there (on the front line), they are trying to get back their positions," the mortar squad's commander, who uses the call-sign Hrai, told Reuters.
"But we have an advantage: despite everything being mined and our soldiers having a hard time, the Russians were thrown out of their positions where the most fortified line of trenches and dugouts was."
"Now the Russians are in the field where they have nothing and they’re trying to build something there. Our soldiers are in their (former Russian) positions, prepared by them (the Russians). That's the advantage we have," he said.
The mortar position is part of a maze of trenches and dugouts with wooden walls and underground living quarters.
"At first we had to make one dug-out. But then we got excited and started digging and digging. We built a restroom, then another room. The longer the war lasts, the more rooms there will be here," Hrai said.
The living quarters have lighting, wi-fi and wooden beds, shelves and furniture. In the kitchen area, a frying pan hangs on a wall and other cooking equipment lies on shelves. Rifles hang on the wall in another area.
"We live like kings, we sleep on bunk beds. We have mattresses, we brought foam rubber to use as mattresses," Hrai said. "We live in comfort: we have heating, electricity everywhere, there is internet connectivity and wi-fi is available right now."
(Writing by Timothy Heritage, Editing by Tom Balmforth)