Trump backed away because no American was killed. Just like he did nothing when Iran shot down our unmanned drone, when Iran attacked oil tankers in the Persian Gulf, and when the Iranians attacked the Saudi oil fields. But when Iran backed militias killed an American contractor and wounded several American soldiers, President Trump ordered strikes on the militia locations, and then when he learned that the Iranian cockroach general was planning larger scale attacks on Americans in the Mideast he took him out with a drone.