The story: Controversy has erupted over the snap inspection of a Beirut-bound Iranian passenger plane and those onboard—including diplomats. Outlets close to centers of power in Tehran allege that Lebanese authorities were influenced by Saudi media reports that the plane was carrying money for Hezbollah, an ally of the Islamic Republic.

The incident has raised questions among observers over the state of Iranian influence in Lebanon. It has also put the spotlight on the trajectory of Iranian-Saudi relations, particularly as Donald Trump is set to...