Ukraine and its international partners must continue fighting to restore Ukrainian control over Crimea, President Volodymyr Zelenskyy said on Monday as Kyiv marked a decade of Russian occupation of the Black Sea peninsula.

Moscow's troops seized control of Crimea in 2014 through a covert invasion, and then used it to help launch its full-scale assault on Ukraine on Feb. 24, 2022.

"This cruel war now being waged against Ukraine was spawned by Russian revanchism precisely when it felt that the world could turn a blind eye to such crimes," Zelenskyy said in a video address.

Ukraine was on Monday marking the 10th anniversary of a rally in the Crimean capital of Simferopol against a Russian-backed movement that paved the way for the annexation, which the international community condemned as illegal.

Russia marks the annexation on March 18, the day President Vladimir Putin formalized it with a treaty in Moscow.

Kyiv has said it will fight on until it restores its 1991 borders, which include Crimea, and is leading a diplomatic push to devise a peace plan that envisions a full Russian troop withdrawal.

Moscow says the idea of peace talks without Russia taking part is absurd and that any settlement of the war would have to recognize the "new realities on the ground."

Ukraine's military is struggling to hold back Russian attacks along the sprawling front line as Russia's invasion enters its third year.

Zelenskyy, in his address, urged Ukraine's partners to "fight for the full renewal of international law."

"We can end this war on our Ukrainian terms. We can return our land and people from the occupation," he said. "We can bring Russia to justice for what it has done. But for this to happen, we must fight."