The most recent propaganda videos from Boko Haram have higher production values than in the past and other similarities to ISIS-produced videos. Boko Haram/Sendvid hide caption

itoggle caption Boko Haram/Sendvid

An armored vehicle used by Boko Haram militants captured by the Nigerian military in Maiduguri, Borno state, late last month. The extremist group appears to be expanding its operations into neighboring countries in an effort to establish an independent Islamic state. EPA/Landov hide caption

itoggle caption EPA/Landov

An official stands in front of relief materials at a camp for displaced people in Maiduguri in Borno State last week. The town, where many have gathered after fleeing Boko Haram attacks, is now said to be under assault from the Islamist extremist group. Reuters/Landov hide caption

itoggle caption Reuters/Landov

Satellite image of dense housing in Doro Baga taken on Jan. 7, following an attack by Boko Haram. This shows almost all the structures razed. The inset demonstrates the level of destruction of most of the structures in the town. The red areas indicate the remaining healthy vegetation. Micah Farfour/DigitalGlobe hide caption

itoggle caption Micah Farfour/DigitalGlobe

A group of Nigerian traditional hunters and vigilantes gather on vehicles on their way to engage Boko Haram militants in Mubi from Yola, Adamawa State, in November. The hunters have being assisting the Nigerian military in their fight against the Islamic insurgents. STR/EPA/Landov hide caption

itoggle caption STR/EPA/Landov

Maureen B. Kabrik, a "#Bring Back Our Girls" campaigner, speaks during a sit-out meeting in Borno in support of the release of more than 200 Nigerian schoolgirls in August. Boko Haram militants, who seized the girls last April, have reportedly captured a key military base in the region. Afolabi Sotunde/Reuters/Landov hide caption

itoggle caption Afolabi Sotunde/Reuters/Landov

Members of the Abuja "Bring Back Our Girls" protest group sit during a march in continuation of the Global October movement. Once again, Boko Haram militants are implicated in killings and mass kidnapping in northeastern Nigeria. Afolabi Sotunde/Reuters/Landov hide caption

itoggle caption Afolabi Sotunde/Reuters/Landov

Civilians who had just recently arrived in Yola prepare to flee again, this time in a large open-top truck headed to the city of Jos. Ofeibea Quist-Arcton/NPR hide caption

itoggle caption Ofeibea Quist-Arcton/NPR

#BringBackOurGirls" campaigners participate in a lamentation parade in Abuja, in early November, as more towns in Nigeria come under attack from Boko Haram. Afolabi Sotunde/Reuters/Landov hide caption

itoggle caption Afolabi Sotunde/Reuters/Landov

Ramatu Usman, shown here with one of her sons, is a 37-year-old mother of eight. She says she was separated from one of her sons, 6-year-old Yahaya Buba, following an attack. He is still missing. Ofeibea Quist-Arcton/NPR hide caption

itoggle caption Ofeibea Quist-Arcton/NPR

People inspect the site of a suicide bomb explosion at the Government Science Technical College in Potiskum, Nigeria, Monday. Survivors say a bomber disguised in a school uniform detonated explosives during an assembly at the school. Adamu Adamu/AP hide caption

itoggle caption Adamu Adamu/AP

People call for the Nigerian government to rescue girls taken from a secondary school in Chibok region, during a protest earlier this month. Boko Haram, the group that took the girls, says they have been "married off." Olamikan Gbemiga/AP hide caption

itoggle caption Olamikan Gbemiga/AP

A man poses with a sign in front of police officers in riot gear during a demonstration calling on the government to rescue the kidnapped girls of a government secondary school in Chibok, in Abuja, Nigeria, on Tuesday. Olamikan Gbemiga/AP hide caption

itoggle caption Olamikan Gbemiga/AP

Earlier this month, people demonstrated in Nigeria's capital, Abuja, calling on the government to rescue girls taken from a secondary school in Chibok region in April. Now there are reports that militants of the extremist Boko Haram movement have kidnapped more girls. Olamikan Gbemiga/AP hide caption

itoggle caption Olamikan Gbemiga/AP

This week, Pakistani activist Malala Yousafzai met with some of the girls who escaped Boko Haram's captivity. The Islamic extremist group gained attention in April when it kidnapped more than 200 girls from a school in northeastern Nigeria. Many girls are still missing. Olamikan Gbemiga/AP hide caption

itoggle caption Olamikan Gbemiga/AP