The NATO Allies are sure that the Syrian regime unleashed chemical weapons against the civilian population and rebel fighters. Russia denies it, and Inspectors may go in to see for themselves what evidence remains from the violence some days later. President Obama made the use of chemical ordnance a red line Assad should not cross, but then decided not to take action when he did. President Trump also made it a red line, and followed a previous case of presumed chemical weapon use with a single surgical strike. This has not deterred the latest incident.
The West is now seeking to establish good evidence of what it believes has taken place, and is considering its military options. These are limited and constrained by circumstance, and by the history of the West leaving much of the Syrian theatre to a combination of Assad and Russian power to deal with Isis. No-one can credibly claim that killing more Syrians is the missing policy in this dreadful conflict that could start to put things right. There have been all too many deaths already, and the West will not wish to add to the death toll of civilians. Taking on the Assad regime and its troops is an unlikely mission, as they are strong on the ground, battle hardened, and understand the people and the terrain. It would entail a huge effort by the West including an invasion. When tried elsewhere the problem has been how to create a replacement government that is stable, has authority and is democratic in such circumstances. Supporting the rebel forces against Assad with air power would be a dangerous mission pitting the West against Russia who would continue to support Assad. There is no evidence that there is a well armed and substantial rebel force with a chance of winning against Assad and Russia who could also create a stable and good government in the end.
This seems to leave Mr Trump with using missiles and smart bombs to destroy known military installations, weapons dumps and any chemical weapons facilities that they have identified. Even this will require great precision and care not to harm people who live near to these facilities, and to deal with any attempt by the regime to organise actual or fake damage to release as bad news following any attacks. Mr Trump may like to involve France and the UK in any such attack to show this is a wider Western alliance action, undertaken by three members of the UN Security Council. It cannot however be done in the name of the UN as Russia has vetoed a proposed resolution on this Syrian atrocity.
NATO needs to ensure that if it does fly missions by fast jets, or send in drones or missiles, it does so without creating a military exchange with Russia. The military airspace over Syria is often used by Syrian and Russian planes. Events can happen quickly when fast jets from Russia and NATO are seeking to use limited airspace for different purposes, and when the fast jets can close on each other with each flying at speeds well in excess of 1000 miles an hour.
What should the UK do? It should of course work with our NATO allies. With them we have condemned any use of chemical weapons, and with them we can examine the options. I also trust the UK will be a sane voice wanting us to act effectively where we can, rather than demanding action to reveal our anger even if there is no action that is likely to have a good outcome.