Russia has announced a cross-border offensive had captured territory in Ukraine's Sumy region for the first time since 2022 as Ukraine struggles to hold onto territory in Russia's neighbouring Kursk region.
Russia's defence ministry also said its troops had recaptured three more villages seized by Ukraine in the Kursk border region, where Ukraine's forces have been losing ground recently.
A ministry statement said they had recaptured the villages of Malaya Loknya, Cherkasskoye Porechnoye and Kositsa, having already claimed gains in the Russian region earlier this weekend.
Ukraine wants to use the territory it holds in Kursk as a potential bargaining chip in any peace negotiations.
US and Ukrainian negotiators are set to meet for talks in Saudi Arabia next week, with US President Donald Trump's administration keen to agree on a ceasefire and a "framework" for a peace agreement.
The US has cut off Ukraine's access to intelligence sharing and satellite data in a bid to force it to negotiate.
The Russian defence ministry said in a briefing that its forces, in a counter-offensive, had "liberated" the small village of Novenke in Sumy near the border with Kursk.
Russia briefly occupied parts of Sumy at the start of its all-out invasion in 2022 but has not conquered any territory there since.
Russian President Vladimir Putin said in mid-February that his forces had entered this part of northeastern Ukraine, a claim branded a "lie" by Ukraine, although it has acknowledged isolated attacks.
Novenke is located about a kilometre from Kursk and Russian military bloggers said its capture brought troops closer to blocking a major Ukrainian supply route.
Ukraine has not yet commented on Russia's claim to have captured Novenke.
Ukraine denies reports of 'massive breakthrough' by Russia
Ukraine's Centre for Countering Disinformation yesterday denied reports of a "massive breakthrough" by Russia, saying its forces were destroying small groups trying to cross the border.
Russia announced the recapture of the village of Lebedevka in Kursk, bringing its troops closer to taking back the Ukraine-held town of Sudzha, about 10 kilometres away.
Ukraine launched its incursion into Kursk last August, seizing territory as a buffer zone.
But since then, Russia has taken back more than two-thirds of the territory.
A Russian army commander, Apti Alaudinov, wrote on Telegram yesterday that "all units have launched a large-scale offensive across all areas on the Kursk section of the front".
A Russian military blogger, Yevgeny Poddubny, wrote that the Kursk incursion "is in its final phase".
Prominent Ukrainian journalist Yuriy Butusov wrote on Sunday that holding onto the Kursk territory was no longer tactically justified.
Yesterday, a Russian assault hit the centre of Dobropillia in the eastern Donetsk region last night, killing 11 people and wounding 40, according to the emergency services
Ukraine confirms Russia used gas pipe to reach town
Ukraine's General Staff confirmed reports that Russian special forces had used an underground gas pipe to reach the outskirts of the main town controlled by Ukraine in the region, Sudzha.
Ukraine said its aerial reconnaissance had spotted the troops, who were "being detected, blocked and destroyed".
Russian military bloggers wrote that troops crawled some 15 kilometres through a pipe with a diameter of 1.4 metres.
They hailed the attack as a feat, said the troops had achieved their objective, and that fighting was ongoing in Sudzha.
Russia supplied gas to Europe via Ukraine until January of this year and Sudzha was a hub for transferring and measuring gas.
Russia also claimed the capture of another village in east Ukraine.
Its troops are advancing in the Donetsk region and are close to crossing a symbolic border into the central Dnipropetrovsk region, which so far has been free of fighting.
The defence ministry said troops had taken the village of Kostyantynopil, around 13 kilometres from the regional frontier and 50 kilometres west of the large Russian-held city of Donetsk.
Russia's advances come as the prospect of peace talks appears increasingly likely, with Ukrainian and US negotiators meeting next week in Saudi Arabia.
US Middle East envoy Steve Witkoff said his team wanted "to get down a framework for a peace agreement and an initial ceasefire as well" at the talks set for Tuesday.
Ukrainian President Volodymyr Zelensky has said Ukraine is "fully committed to constructive dialogue", while wanting its interests to be "taken into account in the right way".
