Russia has intensified its drone attacks on Ukraine, deploying faster, jet-powered drones that are harder to intercept in around-the-clock strikes, with Kyiv among the primary targets. Many of the attacks have focused on infrastructure, including businesses, warehouses, factories, petrol stations, and energy systems.

Ukraine has continued to launch drone strikes deep into Russian territory, largely targeting gas, oil, and business distribution facilities. Both countries deny targeting civilians.

The escalation has continued despite US President Donald Trump sending envoys to Moscow for talks with Russian President Vladimir Putin and to Kyiv for talks with Ukrainian President Volodymyr Zelensky last weekend.

Five people were killed and 67 others wounded in a daytime Russian drone strike on a shopping mall in Pavlohrad, in the Dnipropetrovsk region, on Thursday, according to Ukrainian officials. Earlier in the week, Russian air strikes hit two other shopping malls in Zaporizhzhia and Sumy, killing two people and injuring 28.

Russia reported a Ukrainian seaborne drone attack on the resort city of Sochi overnight on Wednesday, in which 28 people were wounded. Three further deaths were also attributed to Ukrainian attacks. Two people were killed earlier this week when Russian drones struck a border crossing between Ukraine and Moldova, a country that has increasingly found itself drawn into the conflict.

Against this backdrop, a senior United Nations official has warned that Ukraine is heading into its most dangerous winter since Russia launched its full-scale invasion more than four and a half years ago.

Alexander De Croo, a former prime minister of Belgium now serving in a UN role, told sources that the situation was deeply alarming. "This winter is going to be the toughest one since the war," he said.

He said Ukraine was entering the season from "a very weak base" and that UN officials were "very, very worried... about what this winter could become."

De Croo attributed the concern to what he described as Russia's "very systematic" targeting of civilian and energy infrastructure.

"This is petrol stations, it's shopping malls, it's business centres, but it's especially energy infrastructure, energy transmission lines, and so on. There is absolutely no justification for that," he said.

He warned of a worst-case scenario in which people could lose access to heating, while water and sewage systems ceased to function. Winter temperatures in Ukraine can drop to -20C.

"With the temperatures that you would get here that would lead to circumstances which would be really close to humanitarian catastrophe," De Croo said. Severe damage to power supplies and critical infrastructure could lead to "quite some human suffering," he added.

Efforts are under way to prepare Ukraine for the coming months. The UN Development Programme is helping to rebuild parts of the energy system damaged during last winter and is working to establish more sustainable, decentralised energy plants that are less vulnerable to attack.

De Croo described the work as "almost an impossible task," given that it is being carried out under constant threat.

"They are reconstructing these sites under constant, constant air alarms. And they know that they are working at a site which is a target," he said. "So you try to reconstruct, but part of your day you can't work because it's just too dangerous."