( CNN) In a policy change that will induce heads spin, the Trump administration has in the space of a few days run from a hands-off approach to the civil war in Syria to launching of dozens of Tomahawk missiles against a Syrian air base near the city of Homs.

So why the dramatic fulcrum? And what are the key takeaways from this development that has broken years of US reluctance to strike Bashar al-Assad directly?

Chemical weapons assaults genuinely moved Trump