In the long and tangled effort to bring the war in Ukraine toward some form of resolution, Donald Trump stepped forward on Wednesday to claim that Vladimir Putin is willing to negotiate a settlement — an assertion that places a former American president in the unusual role of informal intermediary between adversaries. Trump offered no specifics about when or how he came to know Putin's mind, leaving the claim suspended between possibility and performance. It is a moment that reveals as much about the fragmented state of diplomacy as it does about any genuine opening for peace.