In the latest campaign by the African Islamic militant group Boko Haram, hundreds of gunmen reportedly overtook the town of Baga, its neighboring villages, and a multinational military base.

During a five-day attack in Nigeria's northeast, the heavily armed militant group descended on joint-run African military base, one of the few remaining government-run operations in the area. Upon seeing the gunmen, the military guards abandoned their posts.

In recent days, Boko Haram has attacked and destroyed 16 villages. Official death tolls have not been recorded, but reports vary widely, with anywhere from 200 to as many as 2,000 Nigerians killed, according to Amnesty International on Saturday.

About 10,000 people have fled to neighboring Chad this week, with reports of many drowning in an attempt to cross Lake Chad. Baga has been largely abandoned after what is now described as what may be the “deadliest massacre” in the history of Boko Haram.

“After taking the goods, they put fire, and burn this place,” Alhaji Baba Abahassan, the Baga District head, told The New York Times. “Even now, if they see a man, they will kill you. They killed many people, but nobody has the exact number. If I say this is the exact number of killed, I am telling lies.”

In targeting Baga, a town on the border with Chad and the last area in Nigeria's Borno State where the national government still had a military outpost, Boko Haram is effectively consolidating its control over northeast Nigeria. The group, whose name means strict adherence to traditional Islam and the rejection of Western influences, claims that it wants to develop an Islamic state in a country with mixed religious identities of both Christian and Muslim followers. The group, which gained power in 2009, killed 10,000 people this past year, according to a Council on Foreign Relations report, and the violence continues.

Why is the Nigerian government struggling to stop the bloodshed?

Abubakar Shekau, the leader of Boko Haram, announced in August his mission to establish his Islamic caliphate, a political-religious Muslim state of which he would be the leader. Since its inception, the group has received growing attention for its brutal, violent, and often indiscriminate attacks. In April 2014, they gained international notoriety for the kidnapping of 276 girls from Chibok Secondary School, which prompted the viral hashtag #BringBackOurGirls. Since then, the militant group has continued attacks and kidnappings which the Nigerian government has struggled to effectively counter.

The New York Times reported that Borno State governor, Kashim Shettima, expects Boko Haram to continue in their conquest. “The Boko Haram strategy is to strangulate the city [of Maiduguri], and make it the capital of their caliphate,” he said in an interview from the Nigerian capital, Abuja. “They have captured all the outlying towns. The Boko Haram is better armed than ever before.”

Nigerian President Goodluck Jonathan has pledged to put an end to to the group's reign of terror, but Boko Haram has refused to negotiate with the current government, which is lead by non-Muslim political party. If anything, Boko Haram's attacks are intended to display the government’s inability to effectively respond and influence the outcome of the next election. Boko Haram boasts firepower, discipline, and seems to benefit from links to well-funded organizations such as al-Qaeda.

In 2013, the Nigerian military descended on Baga in response to an attack by Boko Haram fighters. The effort, during which critics accused soldiers of executing more "destruction than protection," at least 37 people were killed and 2,275 homes were destroyed. When Boko Haram overtook Baga on January 3, government soldiers abandoned post left unarmed citizens to defend themselves.

"We are very dispirited," Borno North senator Maina Maaji Lawan told BBC. "There is definitely something wrong that makes our military abandon their posts each time there is an attack from Boko Haram."

On Saturday, Mike Omeri, the Nigerian government spokesman on the insurgency, said fighting continued into Friday for Baga. "Security forces have responded rapidly and have deployed significant military assets and conducted airstrikes against militant targets," Omeri said in a statement.

Following a pattern similar to the one employed by the Islamic State militant group in Syria, Boko Haram is expanding its reach. An analysis by Stratfor Global Intelligence shows that with their newfound ambitions, Boko Haram may expand its territory from Nigeria to Cameroon. The militant group has switched its tactics from insurgent attacks to conquering terrain. Nigeria's ground forces face many constraints, both logistically and resourcefully, made worse by an absence of political support from the central government that leaves troops with low morale. In multiple cases, troops have simply refused orders to mobilize in response to Boko Haram activity.

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In light of recent attacks in Cameroon, Cameroon's president Paul Biya appealed for help during a New Year speech he delivered to diplomats:

“A global threat calls for a global response. Such should be the response of the international community, including the African Union and our regional organizations,” Biya said.

Some of Haram Boko's militants may be part of a larger movement that has attacked Mali, the Central African Republic and Somalia, yet foreign support has been limited. Niger announced that it will not be involved in the process of reclaiming Baga. Chad has also withdrawn troops from the area. Nigeria has struggled to gain international assistance with its air force, due to concerns that airplanes will be used to indiscriminately bomb civilian regions.

The events of the last week have illustrated that the militant group not only has the resources needed to gain territory, but they also have displayed a brutality that “shows no regard” for human life, said State Department spokeswoman Jen Psaki on Saturday.