The Kremlin said on Monday that territorial issues remain fundamental to any agreement to end the war in Ukraine, state news agency TASS reported, following trilateral talks held over the weekend in Abu Dhabi.

President Vladimir Putin has repeatedly said Russia would seek to seize the entire Donbas region by force if Ukraine does not agree to cede it as part of a peace deal. Moscow’s forces currently control around 90% of the region.

“It is no secret that this is our firm position, the position of our president, that the territorial issue, which is part of the so-called Anchorage formula, is of fundamental importance for the Russian side,” Kremlin spokesman Dmitry Peskov was quoted as saying by TASS.

The “Anchorage formula” refers to what Russia claims was agreed between U.S. President Donald Trump and Putin at a summit in Alaska last August, according to a source close to the Kremlin.

Under the alleged understanding, Ukraine would hand over control of the entire Donbas region to Russia, while front lines elsewhere in eastern and southern Ukraine would be frozen as a condition for any future peace agreement, the source said.

Kyiv has repeatedly rejected the idea of ceding territory to Russia, saying it will not hand over land that Moscow has failed to capture on the battlefield.

According to Russia’s state-run RIA news agency, Peskov said Moscow viewed the talks in Abu Dhabi positively, describing them as “constructive.”

The U.S.-sponsored talks ended without an agreement, but further discussions are expected to take place next weekend.