Former Russian President Dmitry Medvedev said on Sunday that recent advances by Russian forces against Ukraine in the Kursk region meant that Kyiv's soldiers were almost surrounded.
In a post on Telegram about the fighting in Kursk, Medvedev wrote: "The lid of the smoking cauldron is almost closed. The offensive continues."
According to Reuters, Russian special forces crept miles through a major gas pipeline near the town of Sudzha in an attempt to surprise Ukrainian forces as part of a major offensive to eject Ukrainian soldiers from the western Russian region of Kursk, pro-Russian war bloggers said.
Thousands of Ukrainian soldiers seized about 1,300 square km of Russia's Kursk region in August last year in what Kyiv said was an attempt to gain a bargaining chip in future negotiations and to force Russia to shift forces from eastern Ukraine.
Russia has been pressing the attack with some success in recent days, with open source maps on Friday showing Kyiv's contingent in Kursk nearly surrounded after rapid Russian advances.
Russian advances in 2024 and US President Donald Trump's upending of US policy on Ukraine and Russia have caused fears among European leaders that Ukraine will lose the war and that Trump is turning his back on Europe.
The United States paused military aid and the sharing of intelligence with Ukraine this month after a meeting between Trump and Ukrainian President Volodymyr Zelenskiy on February 28 descended into acrimony in front of the world's media.
In its daily update on the situation in Kursk, Russia's Defense Ministry said its forces had retaken the village of Lebedevka, as well as seizing Novenke, a hamlet across the border in Ukraine's neighbouring Sumy region.
Yuri Podolyaka, a Ukrainian-born, pro-Russian military blogger, said Russian special forces had walked miles along the inside of the major gas pipeline and some had spent several days in the pipe before surprising Ukrainian forces from the rear near Sudzha.
Sudzha is the home of major gas transfer and measuring stations on a pipeline that used to carry Russian natural gas into the Ukrainian gas transmission system for onward transportation to Europe.