The difference between Al Qaeda and Al Shabaab, two terror organisations that have dominated the news in the past week, lies in their origins.

Al Qaeda was the product of a highly structured and coherent planning programme in the 1980s.

It was borne of the writings of Egyptian scholar and cleric Sayyid Qutb, whose calls for the establishment of an Islamic caliphate found enthusiastic support in the group of militants who poured into Afghanistan to end the Soviet occupation.

There was great method in the manner Osama bin Laden, Ayman Al Zawahiri and their followers set out to establish Al Qaeda.

They created a hierarchical structure with a committee at the top and various cells operating semi-independently from the centre.

They took minutes at all their meetings and had a clear — if overly ambitious — goal.

They aimed to draw the Americans into an attritional war that would lead to the withdrawal of US troops from the Middle East, the collapse of the superpower’s economy and the installation of a Muslim caliphate across the Middle East.

Al Shabaab’s evolution was entirely different. The movement is essentially an accident of history.

Ethiopia’s invasion of Somalia on Christmas Eve in 2006, while it routed the Islamic Courts Union then controlling most of the country, opened up an opportunity for the movement’s armed wing, the Al Shabaab, to win popular legitimacy by waging an insurgency against the Ethiopians.

At that point, Al Shabaab did not pose a credible security threat in the region. Its objectives were mainly nationalist.

It aimed to establish a government in Mogadishu that would impose Sharia law.

Leaders of the group occasionally made threats to unite all Somali peoples in the region, which would involve aggression against the likes of Ethiopia and Kenya.

But those threats were not taken seriously, not least because the Somalis of Kenya, for example, were hardly likely to be enthusiastic about shifting their loyalties to Mogadishu.

The biggest single development that transformed Al Shabaab into the regional and possibly global menace that it has become occurred in the Pashtun-inhabited regions of Afghanistan and Pakistan where Al Qaeda was born.

With the Americans stepping up their bombings against targets in the region from around 2007, militants needed a new safe haven.

They found one in Somalia and changed the character of the conflict there.

The arrival of Al Qaeda fighters introduced new terror methods to the Horn of Africa.

Suicide bombings, previously unheard of in the region, became common fare in Mogadishu.

Improvised explosive devices, which were previously the weapon of choice in Iraq, became newly prominent.

The biggest problem that emerged from this flood of new recruits was ideological.

Leaders such as Sheikh Mukhtar Abu Zubayr, veterans of the Afghan wars, supplanted more nationalist figures such as Muktar Robow.

Sheikh Zubayr sees the war in Somalia as an extension of the global jihad and the quest for an Islamic caliphate.

It is instructive that it was he who made the most explicit claim of responsibility following the Kampala blasts.

Perhaps one of the most lamentable features of the international response to Al Shabaab has been the failure to exploit the divisions within their ranks and instal a broad-based government that isolates the radicals.

Analysts such Rashid Abdi of the International Crisis Group have long advocated this approach.

“The failure to reach out to the moderate nationalists,” he said, “only advances the goals of the radicals. It puts everyone into a race to be seen as being the biggest supporter of the jihadists and diminishes the chances of creating a credible alternative to the militants.”

The window may now have closed for such a strategy, although it is unclear what alternative approaches can be taken.

Certainly, the Kampala attacks demonstrated that some of the leaders of Al Shabaab are even more radical, more willing to inflict casualties on a mass scale than the Al Qaeda recruits who operated in the region in the past decade.

It is often forgotten that before it broke up into dozens of regional groupings, Al Qaeda essentially operated at the local level.

Its leadership expressly forbade shedding of innocent blood and exhorted fighters to target mainly Americans and Israelis.

In the 1998 embassy bombings in Kenya and Tanzania, one of the suspects told investigators that their aim was to get the vehicle carrying explosives into the embassy basement, to maximise American casualties and minimise the number of Kenyan casualties.

The fact that Al Shabaab targeted a crowd watching football further illustrates how callous their brand of terrorism is.

It is hardly possible to imagine bin Laden, a football fan, authorising an attack on innocents watching the World Cup.

Indeed, one of bin Laden’s main agents in the Horn of Africa, Fazul Abdul Mohammed, often used football to win hearts and minds in his hideouts.

When he was planning the attacks on the Paradise Hotel on Siyu Island in Lamu, he established two teams for local youth, named, appropriately, Al Qaeda and Kandahar (after the Afghan city.)

The newly minted terrorists of the Shabaab do not seem to worry about such niceties.

President Obama summed this up in his response to the Kampala bombings when he reflected on the fact that terrorists see Africa “as a potential place where you can carry out ideological battles that kill innocents without regard to long-term consequences for their short-term tactical gains.”

The assault illustrates that the economic gains expected from the East African Community will remain a mirage unless there is a coherent effort to tackle the Al Shabaab menace.

That will be the key challenge exercising minds at the heads of state meeting in Kampala in the next few days.