As the world edges towards a peace conference on Syria, three ideas about the west’s role in the conflict are widely accepted. First, that the longer the conflict goes on, the greater the chances of direct or indirect western military intervention. Second, that there is a deep and bitter division between the US and Russia that is making progress much harder. Third, that the Syrian civil war is dominating western thinking on the Middle East. Few people publicly dispute these propositions. And yet they are all distinctly questionable.

To start with, there actually is no single “western” view on Syria. As the bitter debate on whether to lift the EU arms embargo reveals, European countries are deeply divided. France and Britain want to be able to supply weapons to the rebels. Germany remains very sceptical.

There are also divisions within countries. In the US, John Kerry, the new secretary of state, is an activist who wants to arm the rebels. President Barack Obama remains opposed. On both sides of the Atlantic, the intelligence and security establishments tend to take a more cautious line than the politicians and diplomats.