In an exclusive interview with "Good Morning America," Ukrainian President Volodymyr Zelenskyy said he believes the war with Russia is "closer to an end" than many believe and called on allies to strengthen Ukraine as he arrived in the United States for a week of high-stakes diplomacy.

Despite several months of lobbying, Zelenskyy failed to make the case for using Western weapons in Russian territory, and experts are sceptical that the Kremlin is willing to negotiate on genuine terms any time soon.