Ukraine's General Staff said Wednesday that the military has ascertained Russian war plan documents.
"Following successful operations of the Ukrainian army, Russian soldiers panicked and left some secret documents behind," it said in a statement.
Citing the documents, it said Russia's war plan for Ukraine was approved on Jan. 18 and that it had to capture all of Ukraine within 15 days, from Feb. 20 to March 6.
Russia's war on Ukraine, which began Feb. 24, has met international outrage with the European Union, United States and United Kingdom, among others, implementing tough financial sanctions on Moscow.
Many countries are also supplying Ukraine with weapons and have shut airspace to Russian airlines and banned Russian state-run media.
Russia and Ukraine are set for a second round of peace talks Thursday. The first was held Monday.
Earlier Wednesday, Ukrainians said they were battling on in the port of Kherson, the first sizeable city Russia claimed to have seized, while airstrikes and bombardment caused further devastation in other cities, especially Kharkiv in the east.
Russia's week-old invasion has yet to achieve its aim of overthrowing Ukraine's government but has sent more than 870,000 people fleeing to neighboring countries and jolted the global economy as governments and companies line up to isolate Moscow.
The United Nations General Assembly voted overwhelmingly on Wednesday to deplore the invasion "in the strongest terms." It demanded that Russia withdraw its forces in a resolution backed by 141 of the assembly's 193 members.
Bombing of Kharkiv, a city of 1.5 million people, has left its center a wasteland of ruined buildings and debris.
"The Russian 'liberators' have come," one Ukrainian volunteer lamented sarcastically, as he and three others strained to carry the dead body of a man wrapped in a bedsheet out of the ruins on a main square.
At least 25 people have been killed by shelling and airstrikes in Kharkiv in the past 24 hours, authorities said. After an airstrike on Wednesday, the roof of a police building in central Kharkiv collapsed in flames.
