Ukrainian President Volodymyr Zelensky visited newly liberated Izium in the northeastern region of Kharkiv on Wednesday, five days after the country's forces recaptured the city.
Photographs on the Facebook page of an army unit showed Zelensky at a ceremony in the main square to raise the Ukrainian flag over the city's administrative building. Hanna Maliar, the Deputy Minister of Defense, was also present.
"Earlier, when we looked up, we always looked for the blue sky. Today, when we look up, we are looking for only one thing -- the flag of Ukraine," Zelensky said in a post on the presidential Telegram channel.
"Our blue-yellow flag is already flying in the de-occupied Izium. And it will be so in every Ukrainian city and village. We are moving in only one direction -- forward and towards victory."
"I want to thank you for saving our people, our hearts, children and future," Zelensky said, according to a statement released on the presidential website.
"It has been extremely difficult for you in recent months. Therefore, I ask you to take care of yourselves, because you are the most valuable asset we have," he said.
"It may be possible to temporarily occupy the territories of our state. But it is definitely impossible to occupy our people, the Ukrainian people," he said.
There was a minute's silence at the ceremony to remember those who had been lost during military operations.
Ukrainian forces took back control of Izium on Saturday, marking a huge strategic blow to Russia's military assault in the east.
Izium, which sits near the border between the Kharkiv and Donetsk regions, was under Russian occupation for over five months and became an important hub for the invading military.
Moscow was using Izium as a launching pad for attacks southward into the Donetsk region and Kupyansk, some 30 miles (50 kilometers) to the north of Izium, as a rail hub to resupply its forces.
Russia's collapse in northeastern Ukraine sparked fury from Putin loyalists, who condemned the Kremlin's abandonment of Kharkiv in a rare display of stinging criticism.
CNN's Ivana Kottasová, Tim Lister, Yulia Kesaieva, Denis Lapin, Josh Pennington and Victoria Butenko contributed reporting.