President Volodymyr Zelenskyy of Ukraine was returning from the front line last week when he joined a pivotal call with U.S. President Donald Trump.

Hours earlier, Zelenskyy had visited soldiers defending Ukraine¡¯s northeastern Sumy region against Russian ground assaults. Now, stopping in the small city of Romny, he listened on a secure line with other European leaders as Trump outlined Russia¡¯s proposal to end the war.

Russia, Trump told them, was ready to halt hostilities under a deal involving a territorial exchange between Russia and Ukraine, according to a Kyiv-based European diplomat and a top Ukrainian official who were briefed on the call and spoke on the condition of anonymity to discuss sensitive information. Seeing a chance to broker peace, Trump told those on the line that he would meet one on one with President Vladimir Putin of Russia to try to seal an agreement.