A bottle of syrup made from Siberian berries, legions of dirty socks and a military-issued tea bag stamped with “For Victory!”

For Ukrainian soldiers, one advantage of achieving at least creeping advances in the now month-old counteroffensive in southern Ukraine is appropriating ready-made fortifications from the retreating Russians, who in months of preparations dug deep, well-protected trenches.

For the Ukrainians, eerily enough, it also means living and fighting in positions long held by the Russians — with a huge sprawl of military debris and personal items of Russian soldiers scattered about.

“It’s not very pleasant,” said Pvt. Maksim, a soldier with Ukraine’s 36th Marine Brigade, who has collected a number of curiosities, including what he thinks was a talisman: several bullets covered in sparkles and attached to a key ring.

“It’s our land but it’s not very comfortable to be here,” said the private, who like the other soldiers gave only his first name and rank for security reasons. “It doesn’t feel like home.”

In early June, Ukrainian troops, including thousands of soldiers trained and equipped by the United States and other Western allies, began a counteroffensive aimed at driving a wedge through Russian-occupied southern Ukraine. Lying in wait were thousands of Russian troops stationed in miles of trenches and other fortifications amid tank traps and thousands upon thousands of mines.

The Ukrainian forces are attacking in at least three locations on the Russian defensive front. At their farthest point of advance, they have pushed south to form a bulge about five miles into the defensive lines.

Ukrainian commanders want to reach the Sea of Azov, about 55 miles away across open plains that offer little cover. If they succeed, they will divide the Russian occupied south into two zones, cutting the land bridge from Russia to the occupied Crimean Peninsula and greatly compromising Russia’s ability to resupply its forces farther west.

As they have advanced, the Ukrainians have seized Russian trench lines, bunkers and firing positions in abandoned buildings, but under continual artillery bombardment they have had little time to clear the refuse and abandoned clothing, body armor, ponchos, bedding and leftover military rations of their enemy.

Take, for example, the village of Novodarivka, on the plains of the Zaporizhzhia region in southern Ukraine, south of the city of Orikhiv. A month after soldiers with Ukraine’s 110th Territorial Defense Brigade and other units reclaimed it, the village is still strewn with the detritus of the occupying forces.

In the baking sun on a recent day, the village appeared deserted, with the occasional military vehicle rumbling along the single dirt road between destroyed, abandoned houses, kicking up dust.

Amid the boom of artillery shelling, Ukrainian soldiers hunkered down in the captured Russian trenches. On the village’s main road lay an incinerated Russian tank; in a field nearby, two blown-up American-provided mine-resistant vehicles called MaxxPros.

One grim task has been retrieving the remains of Ukrainian soldiers who died defending the village in the first months of the war as the Russian forces were advancing rapidly.

Seven bodies had been lying in the vicinity since April 2022, said one of the soldiers, Lt. Volodymyr.

The Ukrainians had occasionally flown drones over the village while it was occupied, to make sure the Russians had not moved the bodies. On Wednesday, they finally had the chance to retrieve them. “They were just skeletons” that would have to be identified by their D.N.A., Lt. Volodymyr said.

As for the Russian dead, he added, the Ukrainians retrieved those that could be removed without risk and are covering others in heaps of dirt, to try to control the foul odor. Nevertheless, an awful stench wafted about the trenches, and swarms of flies buzzed everywhere.

In an abandoned house, Russian soldiers had scraped into the plaster walls the names of their hometowns or regions: Vladikavkaz, a city in southern Russia, and Primorye, a region on the Pacific coast, near Japan.

Pvt. Maksim, interviewed in the trenches, had collected a small pile of curiosities left behind, including the cowberry syrup made in Yakutia, a region in northern Siberia. Gesturing to the “For Victory!” brand of Russian tea, he said of its former Russian owner, “he didn’t have time to drink it.”

Speaking of the back-and-forth nature of the fighting, Pvt. Maksim said, “We push them back, they push us back, we push them, they push us, and so on,” adding: “They had a lot of time to dig.”

Soldiers said in interviews that the slow progress was to be expected, given the minefields, trenches and open countryside.

The 110th Territorial Defense Brigade, in contrast to the newly trained and equipped units deployed specifically for the counteroffensive, has been fighting in southern Ukraine for more than a year.

One soldier with the 110th, who identified himself as Sgt. Igor, said his unit has been crawling forward to the relative safety of tree lines between fields to assault Russian trenches, moving in small bursts of a few dozen or hundred yards at a time. Such slow advances were preferable to all-out assaults, he said.

“We need to creep forward bit by bit, with infantry, and break them in this way,” Sgt. Igor said. “Crawl forward, fight them, then dig in again.”

Time must pass, he said, for the advancing Ukrainian soldiers trained by Kyiv’s Western allies to become skilled at fighting in the open farmland.

Soldiers deployed in the area develop a finely tuned ear for the whistles and booms of outgoing and incoming artillery, he said, adding, “You hear it and should understand in a second whether to fall down or not.”

Soldiers must steel themselves to maneuver in the trenches and fire their guns at enemy troops approaching in an assault, even if bullets are zipping overhead, he said.

“Training abroad is not the same as real combat,” he said. “They are gaining combat experience now,” he added, and as they do, the pace of the advance could pick up. American officials have said that the Ukrainian commanders are reassessing tactics after the offensive’s slow start and soldiers’ harrowing forays into minefields.

Green recruits are demoralized when fellow soldiers are wounded or killed, Sgt. Igor said. “Their morale is affected quickly,” he said.

“The soldiers will learn,” he added. “It’s complicated. And yes, it’s going slowly. But importantly, it’s going.”

Yurii Shyvala and Maria Varenikova contributed reporting.