But it wasn't just the brutality of the chemical attack which drove the President.
He used the strike as a cut-through event to demand a Syrian settlement, with he unstated threat of direct military intervention if the bloodshed continued.
The aftermath of the strike will be as important as the action itself, with Russian and Iranian reactions among the most significant.
For starters, a man with a front-row observer's seat to the Trump decision at Mar-a-Lago was visiting Chines President Xi Jinping.
If Russian personnel were hit by the US missiles relations with Moscow will be tense.
Australia, as a Mid East partner, was told, as Prime Minister Malcolm Turnbull has indicated.
And the effect on the Assad government I'll be critical, and will probably begin with a public relations offensive.
US observers are expecting a display of civilian victims - genuine or otherwise - by the Syrians.
But the broader issue is the continued existence of the Assad government, and the possibility of a military coalition forcing regime change.
And what after that?
Syria is a bloody tangle of Islamic extremists, anti-Assad rebels, militant Kurds, encroaching Iranian interests, and thousands of wretched, desperate civilians.
If that cluster is unmanageable, the area could remain violent and unstable.
