What is the UK doing in North Africa?

Algeria had, until recent days, scarcely featured on the mental maps of most British politicians. No prime minister has visited the country since it became independent in 1962.

On his visit to Algiers on Wednesday, David Cameron will stress the strategic importance of one of the largest countries in the world in what he has called "the generational struggle" against al-Qaeda in North Africa.

The prime minister and his Algerian counterpart will pay their respects to those who died in the hostage crisis in the desert. They will also discuss deeper security co-operation as British and French force numbers are increased in neighbouring Mali.

David Cameron insists he is not contemplating another conflict like that in Libya, let alone another Afghanistan. His aides are stressing that the troops being sent to the region are to be used for training, logistics and intelligence, and not combat. They talk of a temporary operation.

Some will point to the fact that where once the talk was of "tens of" British troops it is now hundreds and note that the defence secretary said in the Commons on Monday that it was not the government's "intention" for British troops to play a combat role.

This trip is bound to heighten the demands on the prime minister to say not simply what he is not planning in North Africa, but to explain more about what exactly he is.