The rise of jihadism in Africa is rooted in bad governance,
exacerbated by population pressure and climate change.
When the state is corrupt and predatory, the insurgents’ promise of religious justice can sound appealing.
There is not much outsiders can do to fix this.
Africa’s governments need to step up to their responsibilities.
However, outsiders can help contain the jihadists,
stopping them conquering turf or building anything resembling a state.
This can be done with a light touch, by modest forces, at a reasonable cost.
France already has about 4,500 troops in Africa; America has about 6,000.
These are not many boots on the ground in so vast a region.
Yet they are having an outsize effect by training, supporting and providing crucial intelligence to the African armies that are doing almost all the fighting.
Western forces are helping to hold a fragile region together.
Alas, that appears not to be a priority for President Donald Trump.
Since the deaths of four American soldiers in Niger in October, American troops have been ordered to take fewer risks.
Their commanders have been told to plan for a possible cut of up to 50% in the number of special forces assigned to the region.
The signs are that Mr Trump is about to repeat Bill Clinton’s mistake.
Mr Clinton pulled out of Somalia in 1993, as soon as dead Americans appeared on television.
Somalia later collapsed into anarchy and became a haven for jihadists and pirates.
Stopping the Sahel from falling apart would be easier than putting it back together.
Western troops are insurance against disaster.
Keep paying the premiums.