Ukraine launched an offensive Friday to drive out Russian troops in the northeast part of the country.
The two militaries have been engaged in an arduous battle with neither side able to gain the upper hand, The New York Times reported.
However, Ukrainian troops are rallying to form an offensive against the Russian forces, which are pushing toward key cities in the northeast including Kharkiv and Izium.
“There are fierce battles going on, as well as the transition from defensive operations to offensive actions in the Kharkiv and Izium areas,” Ukrainian Commander in Chief Valeriy Zaluzhnyi said Thursday, according to the Times.
Ukrainian officials have warned, meanwhile, that Russian President Vladimir Putin could intensify attacks on the country during Russia’s Victory Day on Monday.
The holiday commemorates the victory of the Soviet Union over Nazi Germany in 1945, near the end of World War II.
Officials warn that there is a threat of more intense missile strikes over the weekend and on Monday.
Ukraine’s success in its offensive is in part due to the advanced artillery and weapons it possesses thanks to Western contributions to its defense. The West has provided weapons and intelligence, and multiple outlets on Thursday reported the intelligence played a role in the sinking of a Russian warship.