Donald Trump is back. And unlike Europe, the Gulf is not too worried. In contrast with 2016, when Trump won his first term, the Gulf Arab states are in a far stronger and strategically autarkic position: less dependent on the United States and much more strongly interconnected with other parts of a multipolar world order.

At the same time, the Gulf has become more indispensable for American regional policy—providing Gulf capitals with significant leverage. America’s regional posture strongly depends on working through its...