JOHANNESBURG, South Africa – Nigeria has been rocked by a wave of bombings by Islamic militants that have targeted police stations, banks and beer gardens, killing or injuring hundreds of people in recent months.

And now Friday's suicide bombing of the United Nations headquarters in Abuja is a major escalation of extremist violence in the country. The devastating explosion is "an attack on the world," according to Nigeria's minister of state for foreign affairs.

Nigeria's home-grown Islamic extremist group, Boko Haram, claimed responsibility for the car bomb, which tore apart the first floors of the building and killed at least 16 people.

Boko Haram, which means “Western education is a sin,” has targeted government buildings before but this is their largest bomb and comes after months of increasing violence.

The U.N. was reportedly warned last month of a possible attack by the group, which wants full Islamic rule in Nigeria’s northern states and promotes a type of Islam that forbids Muslims to take part in Western-style education, politics and general society.

Boko Haram was previously confined to Nigeria’s northeast, centered on the city of Maiduguri, and the militant group’s activities decreased after a police crackdown in 2009 that resulted in their leader, Mohammed Yusuf, being killed. Boko Haram was viewed as a marginal, local Islamic sect with limited influence and support.

But since Nigeria's general elections in April, the attacks have spread across the nation. The bombing of Abuja’s police headquarters in June killed eight people and led to a curfew across the city; after that attack, Boko Haram warned Nigerians to expect intensified strikes throughout the country.

With increasingly sophisticated weapons instead of the crudely made petrol bombs and bows and arrows of years past, questions are being asked about whether Boko Haram is getting foreign funding and training.

More from GlobalPost: Boko Haram killings shake Nigeria

There are reports that the group has forged alliances with terrorist groups in neighboring African countries, including an Al Qaeda affiliate operating in Mali, Al Qaeda in the Islamic Maghreb. Boko Haram itself has claimed ties with Islamists in Somalia, where the Al Shabaab Islamic militants are fighting for control of the country.

A Western diplomat in Abuja questioned the capability of Nigeria’s police and security forces in dealing with the Boko Haram resurgence, saying that the country can’t handle the increasingly serious threat of domestic terrorism on its own.

“International partners want to work with Nigeria on security issues,” the diplomat said.

The country’s response to Islamic militants will be a critical test of President Goodluck Jonathan’s leadership and his ability to manage Nigeria’s at times unruly security forces.

Damian Ugwu, executive director of the Lagos-based Social Justice and Advocacy Initiative, says the grinding poverty in northern Nigeria and a lack of opportunity for young men have led to the spread of Boko Haram, and President Jonathan must target the root of the problem.

“Because the government is doing nothing for the people, people are open to listening to that ideology,” Ugwu said.

“I suspect that in the coming years they are going to recruit a lot of members because of economic conditions,” he added. “People are frustrated.”

More from GlobalPost: Nigeria's Islamists increase bloody attacks