Ukrainian President Volodymyr Zelenskyy has reiterated that his country will fight until it takes back all of its territory, including Crimea.

Zelenskyy released a video message on Sunday, which is the anniversary of Russia's unilateral annexation of the southern Ukrainian region of Crimea in 2014.

The president said, "Russian aggression began with the seizure of Crimea." He added, "We will return all our people and everything ours from Russian captivity."

On Monday, the Russian presidential office released a video of President Vladimir Putin marking the country's "Special Operations Forces' Day," a holiday celebrating the special units.

Putin praised the personnel participating in what he calls the special military operation in Ukraine, following orders and protecting Russian citizens and territory from the "neo-Nazi" threats.

In an interview with state TV released on Sunday, Putin renewed his determination to press ahead with the Ukraine operation. He said the events of the past year have unified the Russian people. He added that Russia will not lose as long as it maintains this unity.