Lagos - Nigeria's government and military have maintained the narrative for more than a year: Boko Haram, whose bloody insurgency has devastated the country's northeast, is a spent force.In December 2015, President Muhammadu Buhari said the Islamist militants were "technically defeated". Twelve months later, he said troops had run them out of their final enclave.Last month Major General Lucky Irabor, who heads the Nigerian counter-insurgency operation, told reporters the Islamic State group affiliate was "in disarray and... desperate".Throughout January, however, there were repeated attacks in Nigeria as well as in neighbouring Niger and Cameroon, raising questions about the extent of the claims of success.In the latest incident, rebel gunmen on Tuesday ambushed police vehicles on the main road between the Borno state capital, Maiduguri, and the town of Damboa, killing an officer.Last Saturday, as many as 24 people were feared dead when a convoy of civilian buses and trucks with a military escort was ambushed on the same road.There have been hit-and-run attacks against "hard" military targets such as bases while suicide bombers have struck at "soft" civilian targets such as mosques and camps for the displaced. 'Still around' Nigeria's government and its commanders on the ground have repeatedly attributed these recent attacks to the actions of a weakened rebel group lashing out.Last month, reporters were flown in a surveillance plane over the Sambisa forest in Borno state to be shown the military's apparent success in flushing Boko Haram out of its main base, "Camp Zairo"."Each time we are on surveillance mission, we used to see the activities of terrorists here with their vehicles parked under the trees," one air force officer explained on the flight."But now you can't see such things. We have captured and taken over the place from them."Certainly, Boko Haram holds nothing like the territory it did in 2014, when its leader Abubakar Shekau declared a caliphate from the Borno town of Gwoza, threatening Nigeria's sovereignty.But there are fears that instead of defeat and capture, rebel fighters have merely been dispersed throughout the remote region around Lake Chad and are biding their time to regroup.That happened previously in 2013 when emergency rule was declared in three northeast states, including Borno, and Boko Haram was forced out of urban centres.Security analysts tracking the conflict have warned about complacency and underestimating the group's ability to adapt and revert to classic guerrilla tactics.One civilian vigilante leader in Rann, where last month a botched Nigerian air strike may have killed up to 236 civilians, said huge numbers of rebels may have moved in to the area recently."One of those arrested confessed that around 6 000 fighters had moved into villages in the area," he told AFP after a Boko Haram attack on the same town, a day after the bombing.Another militia member in Biu, near the site of Tuesday's ambush, added: "Boko Haram are still around, although they have been badly weakened."Both attacks appear to back up Shekau's claim in a video message in December where he proclaimed: "We are safe. We have not been flushed out of anywhere." Claims 'diluted' Africa security analyst Ryan Cummings said the spate of attacks in January "at the very least dilutes any claims that Boko Haram may be a spent force and thus defeated"."It still comes down to the government erroneously conflating territorial capture with the defeat of Boko Haram, which is incorrect," he told AFP in an email exchange."It is obvious the sect continues to possess the operational capacity to engage in armed incursions against a wide array of targets and is seemingly being more strategic in its employment of violence."Mass casualty attacks against civilians, using suicide bombers, may be designed to draw out security forces from counter-insurgency operations, he suggested.The group appears to be again targeting the military to restock weaponry - as it did in 2013 and 2014 - and camps for the displaced for much-needed supplies.The publisher of the sub-Saharan Africa defence and security forum Beegeagle's Blog said Boko Haram's capacity to launch large-scale hit-and-run attacks was clearly diminished.But they still posed a threat to the military, civilians and humanitarian aid convoys. "BH can only be factually described as being in disarray," he told AFP on condition of anonymity."It would be hasty for anyone to proclaim their defeat at this stage," he said, adding that a response to the switch in tactics was needed.