Iran is pushing the issue with the United States, and is apparently offering a sacrificial pawn on the board (or perhaps knight!) by seizing two British oil tankers alleged to be operating illegally in the Strait of Hormuz.
While it is too soon to predict how the United States and its allies Israel and Saudi Arabia (both sworn enemies of Iran) will react, let's explore the reasons why any US reactionary response will be largely symbolic, even if that involves a token strike versus Iran.
Global alliances have shifted
Turkey has defacto announced its withdrawal from NATO, by its purchase of S-400 missiles. That purchase and collaboration with Russia guarantees its departure from NATO, even if Turkey has not publicly announced such a withdrawal. Furthermore, while Turkey's military bases host US aircraft and operations, Turkey says it will not allow its bases to be used in any attack on Iran, by the US.