This morning four people were killed when two female suicide bombers, including one aged about 15, blew themselves up at a crowded market in Potiskum, northeast Nigeria.
"We evacuated six bodies, including those of the two female suicide bombers, to the hospital. Twenty-one people were injured in the attacks," said a security official in a toll backed up by a health worker
."One of the bombers looked 23 and the other 15," the security official added.
Boko Haram controls about 51,800sq km of territory, an area the size of Belgium. Within this domain, the black flag of jihad flies over scores of towns and villages scattered across the neighbouring states of Borno and Yobe.
The latest conquest was the fishing town of Baga on the shores of Lake Chad, which fell to the Islamists last Thursday.
"For 5km, I kept stepping on dead bodies until I reached Malam Karanti village, which was also deserted and burnt," said fisherman Yanaye Grema.
Boko Haram's fighters have control over 11 local government areas with a total population exceeding 1.7 million.
Its realm stretches from the Mandara Mountains on the eastern border with Cameroon to Lake Chad in the north and the Yedseram river in the west.
The Nigerian army, crippled by corruption and incompetence, has shown itself unable to resist the jihadist advance.
Last September, Abubakar Shekau, the self-styled "Emir" of Boko Haram, proclaimed his ambition to conquer a "Caliphate" and follow the example of Isis (Islamic State).
"There is a copycat element at work here," said Andrew Pocock, the British High Commissioner to Nigeria. "If Isis can declare a Caliphate, then so can we."
There is also a clear practical rationale for Boko Haram to capture territory. "Success, and they have had success, creates a different kind of requirement," said Pocock. "You need a place where you can base yourself and keep equipment and supplies and, indeed, captives. It means that you've got to hold territory."
Shekau has established Boko Haram's unofficial headquarters in the town of Gwoza in Borno. Gwoza is shielded from attack by the volcanic peaks of the Mandara Mountains spanning the nearby frontier with Cameroon. The surrounding area is the homeland of Shekau's ethnic group, the Kanuri.
From this base, Shekau sends his fighters to strike across a vast area. The border with Cameroon means nothing to Shekau, since it slices through the area inhabited by the Kanuri. His men have frequently attacked villages in the neighbouring country, killing 68 of Cameroon's soldiers in the last month alone.
Sometimes, Shekau's goal is to grab more territory, as with the assault on Baga last week. Just as often, he dispatches his fighters on what can only be described as slave raids.
Boko Haram profits greatly from the trade in human beings. Last April, Shekau committed his most infamous act by abducting more than 200 schoolgirls from the town of Chibok, about 80km south-west of Gwoza, triggering a global campaign to "bring back our girls".
By his own admission, the girls were then sold into slavery.
Britain and France stamped out the slave trade in this part of Africa a century ago, but Boko Haram has succeeded in partially reversing this achievement. Today the old caravan routes running north across the Sahara are active again, except that trucks have replaced camels as the means of conveying human cargo.
Boko Haram's name is normally translated as "Western education is banned", yet "boko" means "book" in the Hausa language, so "books are banned" would be more accurate.
In part, Boko Haram is a branch of al-Qaeda's brand of jihadism. As well as seizing towns, Shekau's men carry out suicide bombings in Nigerian cities, including Abuja. Like the Taleban in Afghanistan and Isis in Iraq, they have become expert users of improvised explosive devices. In particular, they have mastered the technique of creating charges that are carefully shaped to destroy armoured vehicles.
In short, Boko Haram have learnt the classic tactics of al-Qaeda.
Yet at the same time, Boko Haram is a Kanuri tribal insurgency. In addition, the movement works as a criminal gang, profiting from theft, extortion and slave raiding. Shekau amounts to a global jihadist, crime boss and tribal rebel leader all at the same time.
If there are limits to his ambitions, they have not been imposed by the Nigerian army. The 7th division was specially created to fight Boko Haram and deployed to Borno. In practice, it does little but try to mount a static defence of Maiduguri, the state capital. In common with the rest of the army, it lacks the mobility and the manpower to challenge Boko Haram's control of the surrounding area. The army may also lack the resolve. Last year, the federal Government allocated 20 per cent of its budget to the armed forces -- more than 4 billion.
Yet precious little trickled down to the soldiers on the front line, who remain poorly armed and equipped. Instead, a large proportion of the military budget simply disappeared into the pockets of senior officers.
Oliver Dashe Doeme, the Roman Catholic bishop of Maiduguri, said that 70 of the 150 churches in his diocese had been destroyed by Boko Haram.
"We have many parishes which have been sacked and overrun. Our major concern is not our buildings but our people who have been driven away from their homes. Some are living in mountains and forests, some are in Cameroon and some have gone elsewhere in Nigeria."
About 10,000 Catholic refugees have gathered in Maiduguri after fleeing Boko Haram's new domain, added Bishop Doeme.
President Goodluck Jonathan, who faces re-election next month, has declared an emergency in the three states most threatened by the Islamists. But Bishop Doeme has no confidence in the army's ability to recapture the lost territory.
"Our main problem is not that Boko Haram cannot be contained, but that you have a deep-seated corruption in high and low places," he said.
"Many of our top military officers are gaining from what is happening here because it means that a lot of money is coming in their direction."
Boko Haram's state
Leader: Abubakar Shekau
The group: Wages Islamic jihad
Known for: Seizing towns, carrying out suicide bombings and using improvised explosive devices
Headquarters: Gwoza in Borno state
Territory: 51,800sq km of 11 local government areas
Population: 2 million people.
- Additional reporting, AFP
