The decision to launch a missile attack on a Syrian Government-controlled airfield represented a complete U-turn in the isolationist policy advocated by Donald Trump when vying for the presidency.  As a former senior British diplomat explains, a week is a long time in geopolitics

If anyone is looking for an intellectually coherent thread to Donald Trump’s foreign policy – a “Trump doctrine” – I have a simple message. Don’t waste your time. Trump is a product of the New York City real estate university of life, where philosophical precepts such as truth, ethics and intellectual consistency hold little sway. He became well used in that university to unsavoury characters. We can only hope that this will equip him to handle the cast of chancers in Moscow, Pyongyang and Syria that he will now be dealing with.

It is clear that Trump sees dynamic decision-making as an end in itself rather than as part of any kind of strategic plan. His decision to order a strike on Shayrat airfield, from where Syrian President Bashar al-Assad had launched his chemical weapons attack on the rebel-held town of Khan Sheikhoun, allows him to characterise his actions as being in stark contrast to those of his predecessor: Barack Obama had warned Assad of serious consequences if “red lines” were crossed, but when they were he did nothing.

Does this mean that the United States has changed tack on demanding regime change in Syria? Only a few days before Assad’s chemical attack, the US had been suggesting that the removal of Assad was no longer a priority. Did this embolden Assad, with or without Russian connivance, to use chemical weapons again, believing he could do so with impunity?