Ukrainian President Zelenskyy said that after negotiators made a breakthrough on security guarantees for Kyiv, his team would move on to discussing “the most difficult issues” with the envoy from Donald Trump.As officials from the United States, Ukraine, and Europe seek to clear remaining obstacles before presenting an agreement to Moscow, the focus of negotiations will shift to previously contentious territorial issues, as well as control over Europe’s largest nuclear power plant—the Zaporizhzhia Nuclear Power Plant—which is currently occupied by Russia.The day before, European leaders expressed appreciation for U.S. support for the security guarantees Kyiv has long sought.Subsequently, U.S. and Ukrainian negotiators will meet again in Paris. Zelenskyy noted that the thorniest issues lie in the territorial status of eastern Ukraine and the fate of the Zaporizhzhia Nuclear Power Plant—which was seized by Russian forces early in the war, now in its fourth year.