Is Trump’s Gulf victory lap a watershed-Gaza may be the litmus test.

Donald J. Trump and the American economy are two beneficiaries of the president’s Gulf road show. So are the Gulf states, Syria, and Make America Great Again supporters within Mr. Trump’s administration. In less than 24 hours in the kingdom, Mr. Trump received a standing ovation from Arab leaders and hundreds of thousands poured into the streets of Syrian towns and cities to celebrate his lifting of long-standing crippling sanctions—a rare achievement for an American president. On the surface, Syrians, Saudis, and Israel critics have much to celebrate, including Syrians’ prospects for reconstruction, Gulf states’ defense, technology, and aviation mega deals with the United States, and seemingly upgraded Gulf relations with the US that potentially put them more on par with Israel. Even so, Mr. Trump has yet to pass the litmus test on whether, how much, and what history he wrote on his Gulf tour, packaged in pomp and circumstance.