DAKAR, Senegal — A sense of fear nags at Hauwa Bulama every time she leaves home.  She worries that suicide bombers might be lurking at the vegetable stand where she shops for her six children. They could turn up at the hospital where she takes her relatives. Any woman in a hijab could have a suicide belt under her clothes, she fears. The frequent public announcements to avoid crowded areas in her northern Nigerian city only heighten her anxiety.  “You are always afraid,” said Ms. Bulama, who lives in Maiduguri, a frequent target of the ruthless Islamist insurgent group Boko Haram. “When you take your child to be immunized, you don’t know who is seated next to you. You don’t know who is hiding what.”  For Ms. Bulama and countless others in northern Nigeria and across the Lake Chad region, the victories scored by President Muhammadu Buhari’s multinational campaign against Boko Haram since taking office in May have mattered little to their daily lives.  Though the Nigerian military has arrested and killed many fighters — and more crucially, retaken a swath of territory once held by insurgents that is estimated to be as large as Belgium — the gains have come against a backdrop of relentless suicide bombings that, if anything, have escalated.  Nigeria’s paradox was highlighted recently when Mr. Buhari told reporters that “technically we have won the war” against the group, a statement that many view as premature. Besides the widespread attacks, the United Nations estimates that more than 2.4 million people in the region — half of them children — have fled their villages in recent years and are afraid to return. The more than 200 secondary schoolgirls from Chibok who were abducted in 2014 are still missing, their whereabouts unknown.  “To state the obvious, this fight is not over, not in Nigeria or in the neighboring countries,” a senior American State Department official said on the condition of anonymity to discuss confidential government assessments. “Our contacts with the Nigerians, both on the military and civilian side, made clear they also share the same basic understanding of the facts on the ground: The suicide bombings will continue.”  Just four days after Mr. Buhari’s declaration, Boko Haram killed at least 50 people in a bombing in Maiduguri, one in a string of vicious attacks at the end of the year that left more than 100 people dead in all. This week, a suicide bomber killed 12 people in an attack on a mosque in northern Cameroon. Last week, the group killed seven people in an attack on a village in northeast Nigeria. They have used children as suicide bombers and have hidden homemade bombs in vegetable carts.  Some Nigerians have criticized Mr. Buhari for boasting of having defeated Boko Haram. Ayo Fayose, the governor of Ekiti State in western Nigeria, sought an apology from the federal government for saying as much after the most recent attacks.  For Mr. Buhari, declaring a technical victory over Boko Haram may have been a matter of saving face. The president, a former army major general who made ridding the nation of the scourge of the insurgency a top campaign pledge, had vowed to defeat the group by year’s end.  Even so, his allies insist that the enduring suicide bombings are evidence that the group has been forced to shift tactics, scattering fighters who are grasping to appear effective. After all, said Brig. Gen. Rabe Abubakar, a Nigerian defense spokesman, suicide attacks can happen even in developed nations that are not at war.  Femi Adesina, a special adviser to Mr. Buhari, said: “The military is out there engaging Boko Haram. The attacks will peter out.”  Obama administration officials and outside experts give Mr. Buhari high marks for reinvigorating his country’s corruption-plagued, poorly equipped military and increasing the fight against Boko Haram, steps they say far exceed the efforts of his predecessor, Goodluck Jonathan.  Mr. Buhari ordered Nigerian commanders to counter Boko Haram in the country’s northeast, much closer to the actual fighting. Arms, equipment and other supplies are now flowing regularly to troops who once complained that they had been forgotten by their civilian leaders.  Mr. Buhari shook up the chain of command, appointing Lt. Gen. Tukur Yusuf Buratai, a native of the northern Borno State, as the army chief of staff. He also made Babagana Monguno, a retired general and another native of the region, his national security adviser. Boko Haram has been driven from nearly two dozen strongholds where it had set up camp.  “In my area, I can really say they have tried seriously,” said Jimmy Peter, whose family lives in Gombi, a town in Adamawa State where soldiers battled insurgents last year. “People have gone back to their homes.”  Even more significantly, several officials said, Mr. Buhari has bolstered relations with neighboring countries like Chad, Niger and Cameroon, embracing the creation of an 8,700-member regional military to combat Boko Haram. The American government recently gave 24 mine-resistant armored vehicles to Nigerians to help the fight.  “The biggest step has been recognizing that they need to work together, that this is bigger than Nigeria and they cannot do it alone,” said Carter F. Ham, the retired Army general who led the Pentagon’s Africa Command until 2013. “That’s a bigger pill for the Nigerian military to swallow.”  American officials warn that with Boko Haram shifting tactics to offset its lost territory, the threat is different, not inherently diminished.  To counter this, experts argue, the military needs to infiltrate the ranks of Boko Haram, to gather intelligence and stop the suicide bombings.  “Orthodox terrorism itself — attacks on urban areas — can only be dealt with by adequate intelligence infrastructure, not by raw military power,” said Chris Ngwodo, a Nigerian consultant and political analyst based in Jos. “The military is only now beginning to build that capability.”  The missing Chibok girls, a cause that still inspires marches on government offices, is a prime example of intelligence shortcomings. Mr. Buhari recently conceded that the military had no credible information about the girls’ whereabouts or well-being. For the first time, he offered to negotiate with leaders of Boko Haram for their release.  For Mr. Buhari, another major hurdle is creating the conditions for the return and safety of the more than two million people displaced by Boko Haram’s violence, officials said.  “Resettlement efforts need to be thought through with international support and extra protection,” said Sarah Chayes, a senior associate at the Carnegie Endowment for International Peace, who spent three weeks in Nigeria, including Maiduguri, in November.  And, at a time of economic strain because of the sinking price of oil, Nigeria still confronts the challenge of rebuilding and retraining its military, which, with about 100,000 troops, is considered small for a country of 190 million people, the most populous on the continent.  “Continued, effective coordination among regional partners is imperative to contain and degrade Boko Haram,” said a senior American defense official who also spoke on the condition of anonymity to discuss confidential government assessment. “As the Nigerian military establishes security, it must be able to transition governance functions to civil authorities, enabling those authorities to address the root causes of support for Boko Haram.”  That means more money for social and economic programs to choke off Boko Haram’s ability to attract new recruits and rebuild trust between civilians and the military, especially after allegations that the military had detained, tortured and killed innocent civilians in its campaign against Boko Haram.  “The Nigerians have a lot of work to do to create better relations between the military and civilians in the northeast, as well as delivering jobs,” the senior State Department official said.  Emmanuel Bonet, director of the Aid Foundation, which tries to prevent youth in northeast Nigeria from joining Boko Haram, said the effort seemed to be succeeding in Damaturu, a city pummeled in 2011 by a string of coordinated insurgent attacks that killed 100 people and injured hundreds.  Many young people recently took part in the International Youth Day celebration for the first time in five years. And Mr. Bonet’s group is building a cafe, complete with Wi-Fi and table tennis and snooker tables to occupy teenagers and 20-somethings.  “Life,” he said, “is gradually returning to normalcy.”  Dionne Searcey reported from Dakar; and Eric Schmitt from Washington. Tony Iyare contributed reporting from Lagos, Nigeria, and Iliya Kure from Kaduna, Nigeria.
Though government forces have killed many insurgents and retaken some territory, a relentless wave of attacks has left many Nigerians living in a perpetual state of fear.