KYIV, Ukraine (AP) — Ukrainian President Volodymyr Zelenskyy said no one knows how long the war in his country will last but that Ukrainian forces are defying expectations by preventing Russian troops from overrunning eastern Ukraine, where the fighting has been fierce for weeks.

In his nightly video address, Zelenskyy said he was proud of the Ukrainian defenders managing to hold back the Russian advance in the eastern Donbas region, which borders Russia and where Moscow-backed separatists have controlled much of the territory for eight years.

“Remember how in Russia, in the beginning of May, they hoped to seize all of the Donbas?” the president said late Saturday. “It’s already the 108th day of the war, already June. Donbas is holding on.”

After failing to capture Kyiv, Ukraine’s capital, early in the war, Moscow has focused on seizing the parts of the largely Russian-speaking Donbas still in Ukrainian hands, as well as the country’s southern coast. Russian forces have been drawn into a long, laborious battle, thanks in part to the Ukrainian military’s use of Western-supplied weapons.