Nonetheless, it is worth remembering that Iraq’s principal problem is political and that a military solution cannot be sensibly pursued without support in nation-building. The endpoint has to be a state that has enough stability to function and can satisfy differing sectarian interests.

There is no reason why the recent ISIS victories have to signal further regional disintegration. Regardless of whether Obama agrees with his predecessor’s Middle East policies, he does have a duty to make sure he does not materially contribute to the further destabilisation of Iraq, Syria and the greater Middle East. America’s action or inaction is still materially significant.

ISIS long ago crossed over from being a symptom of existing problems in the Middle East to being a catalyst for new conflicts. It has considerably weakened the notion that statehood yields security, a condition traditionally reinforced by the international system. Indeed, its aim is to permanently destroy political boundaries. Part of the problem is that by using local proxies Obama has set in motion nationalist rivalries that will actually serve to break the region apart. The defeat of ISIS on the ground by a committed international or US force is relatively straightforward militarily. The harder reality to grasp is that Iraq’s stability and the continued suppression of ISIS cannot be entrusted to regional power players. Iraq and Syria’s future will require a peacekeeping force for a considerable period of time, perhaps led by the UN but ultimately backed by US military power.

The price of inaction should be obvious. ISIS is clear in its desire to start a sectarian war which would probably metastasise throughout the region. So far it is proving surprisingly adept at creating the preconditions. It has successfully established itself as a physical and symbolic rallying point for global jihad. Its online reach has been extraordinary and while the threat of terrorist export is probably limited in numerical terms, the export of an idea has a pernicious effect. The West has a vital interest in preventing its citizens going out to fight and then bringing ISIS’s destructive ideology back with them.