Ukraine’s military has sent reserves to stem Russian advances near two key cities in the eastern Donetsk region, as Moscow attempts to gain more territory before a meeting between its leader, Vladimir Putin and United States President Donald Trump in Alaska on Friday, where land swap issues to end the war will be focal.

The Ukrainian General Staff said on Tuesday that its forces were involved in “difficult” fighting close to Pokrovsk and Dobropillia, with the extra soldiers needed to block attacks by small groups of Russian troops.

The development suggests intensifying struggles in the eastern Donetsk area, where Moscow-backed separatists have mainly held sway since the conflict there erupted there 2014, instigated by the Kremlin and deepened by Russia’s 2022 invasion of Ukraine.

Some of the advancing clusters of Russian soldiers had been destroyed, while others were still being engaged in combat, it added.

Russia’s advance is one of the most dramatic in the past year, with its soldiers infiltrating 17km (10 miles) past Ukrainian lines over the last three days, according to Pasi Paroinen, a military analyst with the Finland-based Black Bird Group.

Moscow, which has further isolated the destroyed town of Kostiantynivka, one of the last remaining urban areas Ukraine holds in the Donetsk, hopes to encircle the nearby city of Pokrovsk.

“A lot will depend on availability, quantity and quality of Ukrainian reserves,” Paroinen wrote on X Monday.

Ukraine’s DeepState blog, which has close connections to the Ukrainian military, described the situation as “quite chaotic”, as Russian troops are “infiltrating deeper, trying to quickly consolidate and accumulate forces for further advancement”.

The Institute for the Study of War, a US-based research group, said Moscow’s advances in the Dobropillia area did not yet amount to “an operational-level breakthrough”.

The Russian advance in eastern Ukraine comes as Europe hopes to rally Trump to Ukraine’s cause at an emergency virtual summit on Wednesday.

Organised by the German Chancellor Friedrich Merz, the meetings are due to be attended by EU leaders, Trump and Ukrainian President Volodymyr Zelenskyy.

In the run-up to the talks, the EU said on Tuesday that it welcomed the US president’s efforts “towards ending Russia’s war of aggression against Ukraine”, but emphasised that “the path to peace in Ukraine cannot be decided without Ukraine” and “international borders must not be changed by force.”

Trump had earlier disappointed his European allies by saying that Ukraine and Russia would have to accept land swaps if peace is to be achieved.

Meanwhile, Zelenskyy has warned that Russia is “not preparing to end the war”, despite Friday’s scheduled meeting between Putin and Trump in Alaska.

“On the contrary, they are making movements that indicate preparations for new offensive operations,” he wrote on X.

In other developments, Ukraine’s SBU intelligence agency said it had successfully targeted a building in Russia’s Tatarstan region, 1,300km (800 miles) from Ukraine, which contained long-range Shahed drones.

Videos shot by local residents confirmed that the facility was hit, the SBU added, noting that it was the second such strike from a great distance in four days.