The United States has formally designated the Nigerian militant sect, Boko Haram, and a splinter group, Ansaru, as foreign terrorist organizations.
Boko Haram's propaganda videos have been some of the public's only windows into the shadowy militant sect.
Sect leader Abubakar Shekau appears in them routinely. He boasts about attacks and threatens enemies ranging from the Nigerian government to Christians to the United States.
A man in recent videos who experts say appears to be Shekau taunts the Nigerian military, which has declared him dead twice.
In a video distributed on DVD to journalists in Maiduguri in early October, the sect shows off large stocks of weapons it says it seized from Nigerian soldiers. Shekau says "a big war" is coming. He says "This war is not about the Nigerian government; it is a war to uplift Islam and get all non-Muslims to repent their ways and embrace Islam. This war is a task that will bring peace, tranquility, equality and fairness in Nigeria."
A charismatic imam named Mohammed Yusuf founded Boko Haram in the northeast in 2002.
People nicknamed the sect Boko Haram after Yusuf's preaching. It means "Western education is forbidden" in the local Hausa language.
The sect wants to establish an Islamic state in Nigeria's Muslim-majority north. Its war with the Nigerian state has killed thousands of people since the insurgency began in 2009.
Yusuf was murdered that same year during a crackdown against the sect. His deputy, Shekau, resurrected what remained of the sect. It reemerged in 2010 more violent than ever.
"He [Shekau] really transformed an organization that was sympathetic to the Taliban and al-Qaida to an organization that operated like the Taliban and al-Qaida. Whereas for Yusuf, it was mostly just preaching and preparing for jihad, but he [Shekau] transformed it from a preaching group about jihad to an actual jihadist group,"
said Jacob Zenn, Nigeria analyst for the Washington-based Jamestown Foundation.
Militants have attacked police and military installations, schools, churches, mosques and the U.N. headquarters in the capital, Abuja. There have been dozens of raids, suicide bombings and drive-by shootings.
Security experts say Boko Haram militants have trained with al-Qaida linked groups in Africa, like al-Shabab and al-Qaida in the Islamic Maghreb.
Experts say what people call Boko Haram is actually several distinct factions. Moderates have split off - some wanting dialogue with the government, others forming new militant groups, like Ansaru, which took issue with the sect's killing of Muslims.
Nigeria launched a massive land and air offensive against Boko Haram in the northeast in May.
Despite the military's reports of success, attacks have continued, not all of them claimed by Boko Haram.