I think the big boys (China, Russia, US) decided behind the scenes that it was time to wrap things up while they could before it escalated out of hand. Russia & China saw the massive US aircraft movements and knew it was a setup for a large strategic bombing campaign which would destabilize the entire region and set a whole bunch of bad precedents in international relations. Someone pulled Trump aside and told him to do a token strike instead and declare victory, giving everyone an off-ramp to stop the shooting for now before things escalate further. America gets to claim its "victory" and Trump gets to hog the spotlight as a "peacemaker", mission accomplished, enjoy your 4th of July.
The Trumptards can keep believing that America is great, Trump is awesome, and everyone in the world fears its military. Meanwhile the rest of the world knows that America is weaker than ever and your president is an emotionally fragile man-child. On top of that you're now seen as agreement-incapable and not to be trusted in any treaties or negotiations after what the US & Israel did to the Iranian negotiation team. The long term damage from that will be far worse than any short term gains from bombing Iran and being Israel's bitch.