
President Volodymyr Zelensky said Ukraine would continue to fight for its freedom in an address to the nation on its independence day.
"We need a just peace, a peace where our future will be decided only by us," he said, adding that Ukraine would fight back against Russia "while its calls for peace are not heard".
He continued: "Ukraine has not yet won, but it has certainly not lost."
Zelensky's remarks came after Moscow said Ukraine had attacked Russian power and energy facilities overnight, blaming drone attacks for a fire at a nuclear power plant in its western Kursk region.
There were no injuries and the fire was quickly extinguished, the plant's press service said on messaging app Telegram. It said the attack had damaged a transformer, but radiation levels were within the normal range.
The United Nations' International Atomic Energy Agency (IAEA) said it was aware of reports regarding the fire, while its director general added that "every nuclear facility must be protected at all times".
The IAEA has repeatedly called on both Russia and Ukraine to show maximum restraint around nuclear facilities in the war.
Independence Day celebrations were held in Kyiv, as the country marked its declaration of independence from the Soviet Union in 1991.
Canada's Prime Minister Mark Carney took part in the celebrations, and stood beside Zelensky at St Sophia's Cathedral as he addressed the crowd:
"I want to say something very simple and important: Canada will always stand shoulder to shoulder with Ukraine."
He said drones, ammunition and armoured vehicles worth more than $1bn Canadian dollars (£534m) would be delivered to Ukraine as early as September, Ukrainian media reported. The deliveries would make up more than half of a support package he announced in July.
Also present was US envoy Keith Kellogg - whom Ukrainian media reported was awarded the Order of Merit, first degree by Zelensky during the ceremony.
After Zelensky thanked him and US President Donald Trump for their support, Kellogg could be heard telling Zelensky: "We're going to make this work".
Andriy Yermak, Zelensky's chief of staff, wrote on Telegram early on Sunday: "On this special day - Ukraine's Independence Day - it is especially important for us to feel the support of our friends. And Canada has always stood by us."
Meanwhile, Zelensky shared a letter from King Charles sending the people of Ukraine his "warmest and most sincere wishes".
"I keep feeling the greatest and deepest admiration for the unbreakable spirit of the Ukrainian people," the King writes. "I remain hopeful that our countries will be able to further work closely together to achieve a just and lasting peace."
Zelensky said the King's "kind words are a true inspiration for our people during the difficult time of war".