Boko Haram leader Abubakar Shekau has appeared in a new video to
 challenge a claim by the Nigerian president and the army that the armed group had been routed
 from its last stronghold of Sambisa Forest .
Shekau last appeared in a video in September where he disputed
 a claim by the Nigerian military that he had been wounded in battle.
"We are safe," he says  in the 25-minute video, flanked by masked 
armed fighters, which appeared on Thursday.
"We have not been flushed out of anywhere. And tactics and strategies
 cannot reveal our location except if Allah wills by his decree."
Referring to Nigerian President Muhammadu Buhari, who said on 
Christmas Eve that Boko Haram had been defeated and driven away from
 the forest, its last
 known bastion, Shekaku says: "You should not be telling lies to the people.
"If you indeed crushed us, how can you see me like this? How many times
 have you killed us in your bogus death?"
It was not immediately clear where the new video was shot, but Shekau,
 who spoke in both Hausa and Arabic, said it was filmed on Christmas Day.
He pledged to continue fighting on until an Islamic state was imposed in 
northern Nigeria.
"Our aim is to establish an Islamic Caliphate and we have our own Caliphate,
 we are not part of Nigeria," he says.
Buhari had announced that a sustained military campaign in the 1,300sq km
 Sambisa Forest in northeastern Borno state had led to the "final crushing 
of Boko Haram 
terrorists in their last enclave in Sambisa Forest".
The government in Abuja and the military frequently claim victories against
 Boko Haram.

Nigerian army claims

Speaking on Tuesday , Brigadier-General Victor Ezugwu, a Nigerian army
 commander, said his soldiers had made significant gains against Boko Haram.
The army has claimed victory over Boko Haram in its stronghold, having
 captured the Sambisa Forest in the country's east over the weekend.
"We are on top of the situation, all hands are still on deck," Ezugwu 
told Our source. "This defeat is final and it [Boko Haram] will not 
spread to other parts of West Africa."
 
Boko Haram's campaign began in Maiduguri, the capital of Borno state,
 though it has since spread beyond Nigeria's borders to Chad, Cameroon
 and Niger.
Nearly 15,000 civilians have been killed since the armed rebellion was 
launched in 1999. The insurgency has forced some 2.6 million others
 to flee their homes since 2009.
The violence has led to a dire humanitarian crisis in the region, with
 thousands of children facing the risk of famine and starvation.