KYIV, Ukraine (AP) – Ukrainian President Volodymyr Zelensky 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 fiercest for weeks. In his nightly video address, Zelensky said he was proud of the Ukrainian defenders managing to hold back the Russian advance in the Donbas region, which borders Russia and where Moscow-backed separatists have controlled much of the territory for eight years.