The US just launched 60 Tomahawk cruise missiles ($30 million) from a warship in the Mediterranean at an airbase where they claim the Syrian bombers at Khan Sheikhoun originated. It’s being reported that the airbase is at least partially destroyed. Since there are thousands of Russian ground troops in Syria, striking them is a concern although apparently Russia was warned in advance of the attack.
The White House isn’t talking yet so it’s speculation that the attack is deterrence to Assad for the gas attack. This is however not the first of Assad’s chemical attacks which are frequent. US policy in Syria is intentionally obfuscated. The US has been bombing in Syria for several years.
We don’t have to understand fully what US strategy is; it’s more than Trump grandstanding but it is not decisive action against Assad. It is not regime-change as Assadists will claim. Our sole mandate is to demand the immediate, unconditional withdrawal of the US & all foreign military forces. US bombers are no more an emancipatory force in Syria than they are in Mosul, Iraq.