Nigeria's Boko Haram Islamist militants have widened their insurgency with their first vehicle-borne suicide bombing in Abuja, heightening concerns they're being trained by al-Qaida's North African group or al-Shabaab in Somalia.

The apparent target of last Thursday's, Inspector General Hafiz Ringim of the Federal Police, was the highest ranking official the group has sought to assassinate since it launched its campaign of violence in Muslim-dominated northeastern Nigeria four years ago.

Until then, all of its attacks, including the killing of security officials, had been confined to that region, where the extremist group has clashed with rival Christians as well as the federal government.

Thousands of people were killed in periodic bouts of sectarian savagery, with Boko Haram showing none of the relative sophistication seen in their recent operations.

"The staging of this attack demonstrates an increased operational area and also could indicate some form of training from transnational jihadists," the U.S. global security consultancy Stratfor observed.

"The bombing … indicates that Boko Haram has had contact with more experienced militants as it has not displayed this level of capability in any of its previous attacks."

There have been unconfirmed reports that Boko Haram, which means "Western education is sacrilege" in the northern Hausa language, has been seeking ties with al-Qaida in the Islamic Maghreb, the jihadist affiliate in Algeria.

AQIM operates throughout North Africa, from Mauritania and Morocco in the west, across the vast ungoverned spaces of the Sahara Desert to Niger in the east.

Niger is oil-rich Nigeria's northern neighbor and thus forms a land bridge from AQIM's main bases in Algeria and Mali.

Boko Haram leaflets, printed in Hausa and circulated in northern Nigeria recently, warned that the group planned to launch a jihad against the Abuja government.

The leaflets claimed that Nigerian militants had returned from Somalia, far to the southeast in the Horn of Africa on the other side of the continent, where they had undergone military training at camps run by al-Shabaab, a jihadist group ideologically linked to al-Qaida.

That was the first intimation of a direct link between the Nigerian sect and al-Shabaab, which is fighting Somalia's Transitional Federal Government, installed and funded by the United States and the West.

A senior Boko Haram leader, Usman al-Zawahiri, said when claiming responsibility for the June 16 bombing that the Somali-trained militants were preparing to launch attacks.

These claims remain unconfirmed, but Stratfor noted "Zawahiri's claims the Somali jihadist group is attempting to train militants in other arenas to conduct attacks cannot be discounted."

The Boko Haram chief isn't apparently related to al-Qaida's new leader, Ayman al-Zawahiri of Egypt, who took over the terror network following the May 2 assassination of Osama bin Laden by U.S. forces in Pakistan.

If the jihadists are indeed driving to expand their operations into the heart of Africa, it would provide Ayman al-Zawahiri, a veteran of Egypt's war against Islamist radicals throughout much of the 1990s, with an opportunity to burnish his new command.

West Africa has the center of a new oil boom, which transforms the region into a strategic zone for the West and China. Big oil and gas strikes have recently been made in East Africa as well.

The upsurge in violence by Boko Haram over recent months followed Muslim-Christian clashes in the central region between the predominantly Muslim north and the overwhelmingly Christian south.

Nigeria's population of around 115 million is split roughly evenly between the two religions.

The most recent bloodletting has been widely attributed to tension stemming from highly divisive presidential, parliamentary and state elections.

The election of southern leader Goodluck Jonathan as president caused anger in the north. The region has few resources, unlike the south, where Nigeria's oil is located.

Analysts say Muslim political barons have instigated the current bloodshed to pressure Jonathan into meeting demands for patronage or face the destabilization of the entire country.

Jonathan is under pressure to crack down hard on Boko Haram. But, Stratfor says, "While this would lessen the violence in the short term, it will not alter the underlying conditions that led to the violence.

"Thus northern Nigeria can expect a long-term cycle of increased violence followed by harsh crackdowns by Nigerian security forces."