Kyiv has announced a string of battlefield successes since it crossed unexpectedly into Kursk region on August 6, but Moscow has steadily inched forward in eastern Ukraine, pressuring troops worn down by two-and-a-half years of fighting.
Olaf Scholz, chancellor of close ally Germany, said he expected Ukraine's push in Kursk region to be a "very limited operation in terms of space and probably also in terms of time," emphasising that Berlin had not been consulted in advance.
Ukraine has closely guarded its overarching aims in the Kursk region, but said that it has carved out a buffer zone from an area that Russia has used to pound targets in Ukraine with cross-border strikes.
A video posted by Ukrainian special forces showed strikes on several pontoon crossings in Kursk region, where Russia has reported that Ukraine has destroyed at least three bridges over the Seim river as it seeks to hold the pocket of captured land.
"Where do Russian pontoon bridges 'disappear' in the Kursk region? Operators ... accurately destroy them," Ukraine's Special Operations Forces said on Telegram messenger.
The incursion into Russia has given a much-needed morale boost to the Ukrainian military. (AP PHOTO)
Ukraine's Foreign Ministry has said Kyiv's advance into the Kursk region has made bigger territorial gains than those made by Moscow in Ukraine this year.
Russia has called the incursion an escalation.
Ukraine smashed through the Russian border in the Kursk region on August 6 in an attempt to force Moscow to divert troops from the rest of the front, though Russian forces have continued to advance in recent days.
Russia took the settlement of Zhelanne, which lies less than 20km to the east of the transport hub Pokrovsk, according to the Russian defence ministry.
Kyiv's military has not directly commented on Russia's advances near Pokrovsk, while reporting heavy fighting nearby.
Both sides reported being targeted by major drone attacks.
Ukraine said it intercepted 50 of 69 drones launched by Russia; Moscow said its air defences destroyed 45 drones over Russian territory, including 11 over the Moscow region.
Reporting back to Moscow, Major General Apti Alaudinov, commander of Chechnya's Akhmat special forces and the deputy head of the defence ministry's military-political department, said that Russia had stalled the Ukrainian incursion.
"We halted them and started pushing them back," Alaudinov told Rossiya state television.
He said Ukrainian forces were regrouping and could soon launch a new attack, though he gave no further details.
Russia has repeatedly said the Ukrainian offensive has been halted.
Ukraine has continued to tout gains and says it has captured 92 settlements over an area of more than 1250 square km.
The incursion has given a much-needed morale boost for the Ukrainian military, which has not made significant gains on its own soil since late 2022.
Roman Kostenko, secretary of the Ukrainian parliament's national defence committee, said Russia's priority remained to capture the Donetsk region despite the incursion and that it was not pulling forces from near Pokrovsk to act as reinforcements.
"The enemy indeed began to transfer some troops... But they have a principal position - not to withdraw troops from the Pokrovsk direction," he was quoted as saying by Espreso.TV media.
Mykola Bielieskov, a research fellow at the Ukrainian National Institute for Strategic Studies, a think-tank in Kyiv, said Ukraine's attacks on bridges and pontoons would help Kyiv to build up a defensive line along the river.
"This is an opportunity to make it more stable, systemic, ready to repel Russian attacks," he said in remarks on national television.
The Ukrainian statement said US-manufactured HIMARS rocket systems had been used as part of operations to disrupt Russian logistics in the Kursk region, Kyiv's first official statement acknowledging its use of the weapon during its incursion.
Washington has not commented directly on the use of US-made weapons in Kursk region, while saying US policies have not changed and that Ukraine was defending itself from Russia's ongoing all-out invasion.