Geneva, Switzerland - Ukraine and Russia made some progress at US-mediated talks in Geneva, but did not find a compromise on the key issue of territory, Ukrainian President Volodymyr Zelensky said Wednesday.

The US has been pushing for an end to the nearly four-year war, which has killed tens of thousands and destroyed much of eastern and southern Ukraine, but Moscow and Kyiv remain at odds over who gets what land in a post-war settlement.

Russia is pushing for full control of Ukraine's eastern Donetsk region as part of any deal, and has threatened to take it by force if Kyiv does not cave at the negotiating table.

But Ukraine has rejected this demand, which is politically and militarily fraught, and signaled it will not sign a deal without security guarantees that deter Russia from invading again.

"We can see that some groundwork has been done, but for now the positions differ, because the negotiations were not easy," Zelensky said in a message to journalists after the talks had finished.

The two sides agreed on "almost all issues" related to a ceasefire monitoring mechanism, which will involve the US, Zelensky said.

But sensitive issues related to the fate of occupied territory in Ukraine's east and the future status of the Russian-occupied Zaporizhzhia Nuclear Power Plant remained unresolved, Zelensky added.

The head of Russia's delegation said the talks were "difficult, but business-like" and that further negotiations were planned for the future.