Mr. Pompeo, who smiled broadly as he greeted Crown Prince Mohammed bin Salman, appeared less intent on determining the truth than in helping the de facto Saudi ruler escape from the crisis he triggered. The Saudis are said to be preparing a cover story that will attribute Mr. Khashoggi’s murder to the excesses of a team that was dispatched to interrogate him. That would deflect blame from the crown prince, who in fact is believed to have ordered and overseen the operation.

Mr. Trump signaled that he is more than ready to assist in that dodge. The president tweeted that in a phone call, the young Saudi leader had “totally denied any knowledge of what took place” — as if that should settle the matter. Mohammed bin Salman grandly declared to Mr. Pompeo, “We face our challenges together — the past, the day of, tomorrow.” “Absolutely,” the grinning U.S. envoy replied.