Under the cover of heavy fog, Russian troops advanced further into the Ukrainian city of Pokrovsk.
In video that emerged late last week, troops were seen entering the city in Ukraine's east on motorcycles and in ramshackle cars, in what was dubbed a "Mad Max-style" convoy.
It was part of what experts say are Russia's efforts to ramp up its battle to take Pokrovsk.
For almost 18 months, the industrial city in the Donbas region of eastern Ukraine has been the site of fierce battles.
Recent drone footage released by news agency Reuters shows pockmarked buildings and shelled-out medium-rise apartment blocks.
But recent reports suggest that just over 1,000 residents from a pre-war population of 60,000 remain living in the city, most without reliable sources of food, and with limited power and heating.
As the temperature drops and winter in Ukraine inches closer — the fourth of the war — Russia is trying to tighten its grip on the city while stretched Ukrainian forces fight to defend a frontline more than 1,000 kilometres wide.
Who has control? It depends on who you ask
In recent weeks, both Ukrainian and Russian officials have claimed they have the upper hand in Pokrovsk.
Reuters reported more than half of the city was "a grey area" controlled by neither side; however, it appeared Russian troops could be close to cutting off supply routes.
The news agency reported there were at least 11,000 troops in the vicinity, with several thousand in surrounding areas.
This month, Ukraine sent special forces to the embattled city to deal with what news outlets have described as "an intense assault" from Russia.
In a briefing last week, Ukrainian President Volodymyr Zelenskyy said Russia's assault on the city was aimed at showing "success on the battlefield".
"It is very important for Russia to do everything to really capture Pokrovsk — in any format," he told Ukrainian state media.
"Whether it is going to be Vovchansk [a city four hours north of Pokrovsk], or something else. They need to show success. Then they will be able to … try to return the narrative: 'We told you that we will capture Donbas.'"
He also said the situation in Pokrovsk remained difficult, in part because "weather conditions" favoured Russian forces.
War of attrition
Despite ramping up efforts, Russian infantrymen are making very slow progress, in part due to the emergence of drone warfare, said Mark Edele, a historian from the University of Melbourne.
He said progress on the battlefield was typically happening at a "crawling pace".
"The kind of extremely static front lines of World War One have re-emerged. The artillery and the machine gun and mines and entrenchments made it difficult to advance quickly," Professor Edele said.
While tanks allowed forces to gain ground in WWII, he said, the presence of drones on the battlefield has reduced the effectiveness of tanks.
"With drones, you can create very deep kill zones, which tanks simply cannot survive, which means you cannot break through with infantry supported by tanks."
According to Professor Edele, in Pokrovsk and in other battlefields across the country, Russians are advancing with very small groups — sometimes as small as three soldiers — staying undetected as they move in to attack Ukrainian defenders.
Kateryna Stepanenko, a Russia research fellow at American think tank The Institute for the Study of War, believes it is likely Russian forces will "close the pocket" between the cities of Pokrovsk and Myrnohrad — but it is unclear how long it will take.
"Russian forces do have a significant manpower advantage in the sector," she said.
The Institute for the Study of War publishes maps that use geo-spatial data to try to show how the war is advancing.
Its most recent update on the Pokrovsk-Myrnohrad area shows counterattacks by Ukrainian forces within the city and on its western outskirts to prevent further advances by Russian troops to the south as they work to encircle the city.
It is unclear how many Ukrainian troops are fighting in the city, or how many Russian soldiers are in Pokrovsk itself, but Mr Zelenskyy claimed there were about 300 Russians in the city, with constant assaults underway.
Russian state-funded media outlets have reported that Ukraine is losing control of the city and that Russian troops are advancing north.
An industrial heartland in ruin
Pokrovsk is considered the gateway to Donbas and the key to allowing Russia to capture the rest of the region.
It is considered a major strategic hub with road and rail junctions that have served as supply routes for the Ukrainian military since the beginning of the war.
It is also coveted by President Vladimir Putin because it has a large Russian-speaking minority, Professor Edele said.
"When it became clear that the takeover of all of Ukraine was a military impossibility, they instead focused on the easier parts where they could mount a case about liberating the Russian minority," he said.
He said the catch would be, however, that if Russia did take the Donbas, it would have to rebuild the destroyed industrial region "almost from the ground up", which would be extremely costly.
Professor Edele said if the city did fall, it would give Russia a new "jumping off" point into other major cities in the Donbas — such as Myrnohrad, Selydove and Kurakhove.
He said while the fall of Pokrovsk would "probably not be a game changer", it would straighten the frontline.
"Militarily, it's important for Ukraine because they've built a strong fortification belt through this region," he said.
"Giving that up would mean they would have to re-establish something similar."
Even though the casualties have been "dramatic", with a recent study estimating 1 million Russian soldiers have now been killed or injured, Professor Edele said the country's population was so big and the fact that soldiers were being well paid to fight meant finding recruits would not be an issue.
"As long as Putin is in place and as long as the income of the Russian state through export of oil and gas cannot be cut off, they can sustain the war effort," he said.
Many residents displaced from Pokrovsk have fled to other areas of Ukraine.
Iryna Kovtunenko, 31, who moved to Dnipro, south-east of Kyiv, after fleeing the city in 2022, told Reuters she despairs about the current situation.
"Where should I come back? There's no place to come back to. I don't have an apartment there anymore," she said.
"Everything is ruined. If I could turn back the time, and everything was good there, and I was asked if I wanted to go back home, I would say 'yes.'"
