The peninsula, which was illegally annexed by Russia in 2014, has long been coveted by Moscow, who want Ukraine to officially surrender the territory as part of a peace deal - something Ukraine does not want to do.

Russia’s illegal seizure of Crimea from Ukraine 11 years ago was quick and bloodless. But Kyiv and most of the world never recognized Moscow’s annexation of the strategic peninsula.

The Trump administration is urging Russia and Ukraine to finalize a deal this week, calling on both sides to "finish it off" or the U.S. may walk away from mediating peace.