It has been a head-spinning week watching the Trump administration stumble into its first international crisis only to emerge with a transformed policy on the use of force in the Middle East, announced on Thursday with the unleashing of 59 sea-launched cruise missiles against the regime of Bashar al-Assad in Syria.

While the limited missile strike was a commendable and overdue response to the use of chemical weapons and to countless other war crimes perpetrated by the regime in Damascus, the public performance of President Trump and his team throughout this tragic episode hardly inspires confidence. On the contrary, the administration demonstrated a dangerous degree of incoherence and inconsistency.

Consider the chronology. The debacle began with a remark by the new United States ambassador to the United Nations, Nikki Haley, in New York at the end of March. Despite a brutal six-year civil war in which Mr. Assad’s forces have been responsible for the deaths of about 200,000 civilians, and despite near universal opposition to his rule by leaders of the civilized world, Ms. Haley thought it was the right time to send a signal to Mr. Assad and his allies, Russia and Iran, that the new American president’s priority “is no longer to sit there and focus on getting Assad out.” Secretary of State Rex Tillerson confirmed this new view, which Sean Spicer, the White House spokesman, described as a simple recognition of “political reality.” Intentionally or not, American policy with respect to the world’s worst military and humanitarian crisis had been changed dramatically.

The unsurprising consequence of this shift was a newfound confidence within the Assad regime that it need not worry about paying a heavy price if its forces committed new acts of barbarity aimed at demoralizing the nation’s remaining rebels. And sure enough, the Syrian Air Force soon began dropping nerve gas on civilian neighborhoods in an insurgent-held town in Idlib province.