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.