President Donald Trump’s suggestion that Ukraine should recognize Russia’s control over Crimea, the southern Ukrainian peninsula Moscow siezed by force more than a decade ago, is threatening to upend international law and order.

A new U.S. peace plan offered to Russia and Ukraine proposes American recognition of the peninsula, which Moscow seized in 2014.

Volodymyr Zelenskiy acknowledged that Ukrainian forces would be unable to regain control over Crimea and said the US won’t have to commit troops as part of security guarantees in an apparent overture to President Donald Trump.