Kremlin demands for Ukraine to cede territory in the Donetsk region to Russia for a ceasefire could hand Moscow a big battlefield advantage, the Institute for the Study of War ( ISW ) has said.

Ahead of a summit between President Donald Trump and Vladimir Putin in Alaska next week, reports cited by the ISW say the fate of Ukrainian territory Russia partially occupies could be given up to Moscow in exchange for an end to the fighting.

The Washington, D.C, think tank said that surrendering strategically vital unoccupied territory in the Donetsk region could force Ukraine to abandon its main defensive line in the region known as the "fortress belt."

Newsweek has contacted the Ukrainian Defense Ministry for comment.

Why It Matters

The fortress belt is made up of four large cities

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