In 2003 the Americans left Saudi Arabia, but now hundreds of American troops will deploy to an airbase outside Riyadh as tensions spike between Iran and its allies and the Trump administration and crown prince Mohammad bin Salman. The deployment of American troops in the kingdom was never popular with Saudis, and comes as their Arab allies desert the crown prince’s war in Yemen. Bringing the Americans back now underscores the king’s deep concern about the regional situation. The American violation of the Joint Comprehensive Plan of Action last year, a move Riyadh encouraged, has set Washington and Tehran on a collision course. Iran cannot allow its oil exports to be curbed by sanctions. The government-controlled Saudi press has openly called for American military action in response to Iranian attacks on oil tankers.