Nigeria's military has been ordered to strengthen its response to Boko Haram after 69 people were killed in an ambush earlier this week, the government said on Sunday.Vice-President Yemi Osinbajo held emergency talks with top brass to discuss Tuesday's attack, which targeted an oil exploration team in the northeastern state of Borno.The attack was the worst since February 2 last year, when 58 people were killed in a twin suicide bomb attack at a camp for the displaced in the Borno town of Dikwa.Osinbajo's spokesman Laolu Akande said the vice-president, standing in for President Muhammadu Buhari who is on indefinite sick leave, called the attack "appalling".The meeting with commanders on Thursday saw Osinbajo issue "fresh directives... to immediately scale-up their efforts and activities in Borno state... to maintain a strong, effective control of the situation", he added.The ambush near Magumeri left 19 soldiers, 33 militia members and 17 civilians dead, sources told AFP, while three staff members from the University of Maiduguri were kidnapped.Boko Haram published a video of the trio on Friday night in which they appealed to Osinbajo to meet their abductors' demands.Analysts have said the attack, apparently by the Islamic State-supported faction headed by Abu Mus'ab al-Barnawi, was an indication of a newly emboldened Boko Haram.Nigeria's military has long maintained that the terrorist group, which in 2014 held territory across northeast Nigeria, is all but defeated as a result of its sustained counter-insurgency.Osinbajo acknowledged that "pockets of terrorists have been launching attacks recently in Borno state".But he said the government was "on top of the situation [and] will define the end of these atrocities by both winning the war and winning the peace in the northeast".At least 20,000 people have been killed in the militant insurgency since it began in 2009.The exploration team from the Nigerian National Petroleum Corporation was hunting for crude in the Lake Chad basin as part of efforts to diversify supply and boost reserves. Osinbajo said the ambush would not prevent the process.