Nigeria's new President Muhammadu Buhari has promised on Friday to end a deadly insurgency by Boko Haram group, an effort he said begins with relocating the military command to Maiduguri, the birthplace of the insurgency."The most immediate (of our security challenge) is Boko Haram's insurgency," Buhari said in his inaugural speech after he was sworn in as Nigeria's sixth democratically elected leader on Friday."Progress has been made in recent weeks by our security forces but victory cannot be achieved by basing the Command and Control Centre in Abuja. The Command Center will be relocated to Maiduguri and remain until Boko Haram is completely subdued," he added.Nigeria is battling a six-year Boko Haram insurgency, especially in its northeastern region, where tens of thousands of people have been killed and millions displaced.Last year, Boko Haram militants seized several towns and villages-across a swathe of Nigerian territory the size of Belgium-while stepping up attacks in the northeastern Adamawa, Borno and Yobe states.The Nigerian army, however, assisted by troops from neighboring Chad and Niger, has since managed to roll back much of the militant group's gains, retaking most of the captured towns.Buhari vowed to rescue scores of schoolgirls abducted by Boko Haram militants from the northeastern Chibok town last year."We cannot claim to have defeated Boko Haram without rescuing the Chibok girls and all other innocent persons held hostage by insurgents," he said."This government will do all it can to rescue them alive," Buhari vowed.The newly-inaugurated leader said that his government will commission a sociological study to determine the causes that led to the rise of Boko Haram."For now the Armed Forces will be fully charged with prosecuting the fight against Boko Haram," Buhari said."We shall overhaul the rules of engagement to avoid human rights violations in operations. We shall improve operational and legal mechanisms so that disciplinary steps are taken against proven human right violations by the Armed Forces."