The Ukrainian counter-offensive in the north-east of the country has reshaped the war that has now passed its 200th day.
Dozens of towns have been recaptured and three key cities, Izium, Kupiansk and Balaklyia in Kharkiv province have swiftly fallen.
It is Moscow’s worst defeat since its troops were pushed back from the capital Kyiv in March and could prove to be decisive.
Ammunition stockpiles and equipment was abandoned by thousands of Russian soldiers when they fled.
The Russian forces had to pull back thousands of their troops after the series of defeats in the north-east.
President Volodymyr Zelenskyy has said Ukraine has retaken around 2,000 square kilometres of territory from Russia since the counter-offensive began earlier this month.
In his Saturday night address, he said: “These days, the Russian army is showing its best – showing its back,” he said in his Saturday night address.
“And, in the end, it is a good choice for them to run away. There is and will be no place for the occupiers in Ukraine.”
The counter-offensive comes as the state agency in charge of the Russian-held Zaporizhzhia Nuclear Power Plant in Ukraine said operations had been fully stopped on Sunday.
In response to the Ukrainian counter-offensive in Kharkiv province, Russia targeted infrastructure facilities in central and eastern Ukraine.
Ihor Terekhov, the mayor of Kharkiv city, said power and water were knocked out in much of the city and described it as “revenge” by Russia for Ukraine’s recent success.
There were also blackouts reported in multiple eastern cities, potentially affecting millions of civilians.
Zelenskyy called these strikes terrorist acts and “the goal is to deprive people of light and heat”.
“Even through the impenetrable darkness, Ukraine and the civilized world can clearly see that these are acts of terrorists,” he said.
“[They are] deliberate and cynical missile strikes on critical civilian infrastructure. Not military facilities.’’
Russian leadership has remained silent with no comments on the defeats at this time from Vladimir Putin or Russian defence minister Sergei Shoigu.
Zelenskyy said that these next three months are going to be crucial.
“Ahead are 90 days that will determine more than 30 years of Ukrainian independence,” he said.
“Ninety days that more than all other years will determine the existence of the EU. The winter will determine our future.”