Ukrainian President Volodymyr Zelensky said in his evening address that the conflict with Russia "must end with Crimea - with its liberation."
"The Black Sea region cannot be safe as long as Crimea is occupied," he said.
"There will be no stable and lasting peace in many countries on the shores of the Mediterranean Sea as long as Russia is able to use our peninsula as its military base," Zelensky said.
British military experts said Russian troops were focusing on repelling a Ukrainian counter-offensive in the country's south.
The US State Department on Tuesday announced plans to provide $89 million in funding to help Ukraine address "urgent humanitarian challenges posed by explosive remnants of war created by Russia's brutal war of aggression," including landmines, unexploded ordnance, and improvised explosive devices.
The plans include deploying around 100 demining teams and supporting a training and equipping project to strengthen the Ukrainian government's demining and explosive disposal capacity.
