Russian forces have made a sudden thrust into eastern Ukraine near the coal mining town of Dobropillia, a move that may be designed to increase the pressure on Kyiv to give up land as the US and Russian presidents prepare to meet.

Ukraine’s authoritative DeepState war map showed on Tuesday that Russian forces had advanced by at least 10 km (six miles) north in two prongs in recent days, part of their drive to take full control of Ukraine's Donetsk region.

The advance is one of the most dramatic in the last year. DeepState said the Russians had surged forward near three villages on a section of the frontline associated with the Ukrainian towns of Kostyantynivka and Pokrovsk, which Moscow is trying to encircle by exploiting Kyiv's lack of manpower.

"The situation is quite chaotic, as the enemy, having found gaps in the defence, is infiltrating deeper, trying to quickly consolidate and accumulate forces for further advancement," DeepState said on its Telegram channel.

US President Donald Trump and Russian President Vladimir Putin are expected to discuss a possible deal to end the war in Ukraine when they meet in Alaska on Friday. Unconfirmed media reports say Putin has told Trump he wants Ukraine to hand over the part of the Donetsk region that Russia does not control.

There was no immediate comment on the advance from Moscow. Ukraine's top military commander, Oleksandr Syrskyi, had ordered reinforcements to be deployed "to detect and destroy enemy sabotage groups that penetrate the line of defence," Andriy Kovalov, a spokesperson for the Ukrainian army, told Interfax-Ukraine.

He said Russia was using its numerical superiority to try to infiltrate Ukrainian defence lines in small groups and had made 35 attempts to push back Ukrainian units, suffering heavy losses in the process. Viktor Trehubov, another Ukrainian military spokesperson, played down the development, saying the infiltration did not amount to a breakthrough.

Pasi Paroinen, a military analyst with the Finland-based Black Bird Group, said the situation had escalated rapidly, with Russian forces infiltrating past Ukrainian lines to a depth of roughly 17 km (10 miles) during the past three days.

"Forwardmost Russian units have reportedly reached the Dobropillia – Kramatorsk road T0514 and Russian infiltration groups have also been reported near Dobropillia proper," he wrote on X.

RUSSIA MAY GAIN LEVERAGE FOR TRUMP TALKS

Tatarigami_UA, a former Ukrainian army officer whose Frontelligence Insight analysis tracks the conflict, posted:

"In both 2014 and 2015, Russia launched major offensives ahead of negotiations to gain leverage. The current situation is serious, but far from the collapse some suggest."

Sergei Markov, a former Kremlin adviser, said the Russians had been able to advance due to "a partial collapse in the front" due to Ukraine's shortage of soldiers.

"This breakthrough is like a gift to Putin and Trump during the negotiations," Markov said, suggesting it could increase pressure on Kyiv to cede some land to prevent the Russian army eventually taking the rest of Donetsk by force.

To do that, though, Russian forces would first need to take control of Sloviansk, Kramatorsk, Druzhkivka and Kostiantynivka - which Russian military analysts call "fortress cities".

Ukrainian President Volodymyr Zelenskiy has publicly pushed back against the idea of ceding territory to Russia, saying any peace deal must be a just one.

Bohdan Krotevych, former chief of staff of Ukraine's Azov brigade and a National Guard lieutenant colonel, took to X late on Monday to warn Zelenskiy of the threat, saying the frontline in the area was "a complete mess".

"The line of combat engagement as a fixed line does not actually exist," he said.