Increasing numbers of Boko Haram attacks against troops have raised questions about the group's current strength, capability and support, as Nigeria's main opposition seized on mounting casualties to criticize the government's record on security before next year's election.
AFP has reported at least 17 attempts to overrun army bases since July, most of them in the remote northeast state of Borno, which has been the epicentre of the nine-year conflict.
A strike this weekend on a base in Metele village, near the border with Niger, killed at least 44, according to security sources, although unconfirmed reports put the death toll much higher.
More than 27,000 people have been killed since 2009 and some 1.8 million are still homeless, while aid agencies are battling the humanitarian fall-out of the fighting.
Nigeria's President Muhammadu Buhari made defeating the Islamist insurgents a key plank of his 2015 election campaign and has said the jihadists were "technically defeated".
But the repeated attacks, many of which have been claimed by the IS-backed Boko Haram faction, the Islamic State West Africa Province (ISWAP), have cast doubt on the truth of that claim.
Security analysts tracking the conflict said more attacks were expected in the run-up to Feb. 16 next year, when Nigerians go to the polls to elect a new president and parliament.
But Yan St-Pierre, a counter-terrorism specialist with the Modern Security Consulting Group (MOSECON) in Berlin, said there were implications beyond Nigeria's borders.
The intensity and regularity of recent attacks indicated ISWAP now had "a capacity for sustained warfare" and "a significant number of fighters and materials" at its disposal.
Asked whether that meant external support from IS remnants from elsewhere, he told AFP: "Without a doubt."
He added: "ISWAP's attacks occur against military and foreign targets with increasing frequency in Nigeria, Chad and Niger, with an increasing presence in Cameroon."
That "not only demonstrates that ISWAP has the capacity and the mobility to successfully organize attacks in multiple areas but that its interests are fully regional", he said. "Put in the context of expanding IS activity in the Sahel -- especially eastwards -- this regional focus is an important change that affects ISWAP military operations."
Seven local employees of a French drilling firm and a government official were killed in southeast Niger on Thursday when suspected Boko Haram gunmen stormed their compound.
Eight Chadian soldiers were killed in an attack in the Lake Chad region last month. Both areas are known hotspots for Boko Haram activity. Nigeria's government and military have not commented publicly on the latest deaths in Metele and have strongly denied previous reports of heavy casualties.
But Buhari's main challenger at next February's election, Atiku Abubakar of the Peoples Democratic Party (PDP), sent a condolence message to the families of those who were killed.
He said the losses were "a clear sign that our troops need to be better funded and better equipped", after soldiers complained of being over-stretched and underresourced.
On Thursday night, Senate leader Bukola Saraki, a Buhari critic who defected from the ruling All Progressives Congress (APC) to the PDP earlier this year, also spoke out about the deaths. He announced that a delegation of senators would travel to the northeast to visit frontline troops, as others in the party questioned the effectiveness of the counterinsurgency.
"It is time that we face the reality that Boko Haram is not technically defeated," said Peter Ayodele Fayose, a former state governor and leading PDP figure.
Amaechi Nwokolo, a security analyst at the Roman Institute of Security Studies in Abuja, told AFP: "The whole thing [the insurgency] has been politicized.
"Now, as election season and Christmas approach, we are likely to see an upsurge in attacks. These terrorists are not dumb. They will certainly want to create chaos around the election."
Political analyst Chris Ngwodo said the PDP would likely want to make capital out of the current situation but added it had not translated into a loss of support for Buhari or the APC.
"I can't see that these attacks have shifted public opinion here," he said from the Borno state capital, Maiduguri. "Borno still feels like Buhari territory.
"The opposition will look for chinks in the armour of the ruling party but I don't know if they can generate the kind of traction from these kinds of incidents."