The leader of the Nigeria-based Islamic State (ISIS/ISIL) wing Boko Haram is reportedly featured in a video recently posted on social media denying claims by the Nigerian military that he had been seriously wounded and warning, “you have not seen the worst yet.”

“You broadcast the news and published it in your media outlets that you injured me and killed me and here I am,” said a man claiming to be the jihadist group’s leader, Abubakar Shekau, in a video addressed to “tyrants of Nigeria in particular and the west of Africa in general,” according to Reuters.

“I will not get killed until my time comes,” Shekau added in the nearly 40-minute video posted Sunday on YouTube and delivered in Arabic and Hausa, which is spoken widely in northern Nigeria.

“Oh tyrants, I’m in a happy state, in good health and in safety,” he also said, according to Sky News.

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Following the release of the video, Sani Usman, a Nigerian army spokesman, issued a statement saying the man claiming to be Shekau in the recently released footage was “unstable” and came as “another sign that the end is near for him.”

“Boko Haram terrorism as it was known, is gone for good. We are just counting down to the day when all the few remnants will be totally wiped out or brought to justice,” he added, without explicitly specifying whether the Nigerian army believed the man in the video to be the Boko Haram leader, notes Reuters.

Near the end of August, the Nigerian armed forces, which has been combating the jihadist group under the leadership of Shekau since 2009, was forced to walk back its allegation that the Boko Haram chief had been “fatally wounded,” saying instead that he had only been injured.

The new video surfaced nearly two months after the Nigerian military claimed to have completely eradicated Boko Haram in its stronghold of northeastern Nigeria.

That claim was reportedly shattered nearly a month later, at the end of August, when the ISIS branch killed 10 people and abducted 13 others, including women and children, during a raid on a village near the town of Chibok in northeastern Nigeria’s Borno state, where the African terrorist group kidnapped nearly 276 schoolgirls in 2014.

The terrorist group’s primary stronghold has been identified as the Sambisa Forest, which covers parts of the northeastern Nigerian states of Borno, Yobe, Gombe, Bauchi, and Kano.

Although the jihadist group no longer controls large swathes of northeastern Nigeria, Boko Haram remained capable of inflicting fatalities and injuries on the Nigerian army as of last weekend.

Reuters reports:

In recent years, the Nigerian military has said it has killed or critically wounded Shekau on multiple occasions, often swiftly followed by video denials by someone who says he is Shekau. Last month Nigeria’s air force said it had killed senior Boko Haram members and that Shekau had been wounded.

While the ensuing videos all show someone sporting Shekau’s distinctive beard, the grainy quality of the footage means it is not always possible to confirm if the person is the same as in the previous videos.

The statement from the Nigerian air force last month was issued days after ISIS, to whom Boko Haram has pledged loyalty, appointed a new leader for the West African group in an apparent rejection of Shekau.

Reuters reports:

That appointment was later dismissed in a 10-minute audio clip on social media by a man purporting to be Shekau, exposing divisions within the jihadist group that has plagued Nigeria and neighbors Chad, Niger and Cameroon.

Boko Haram has killed about 15,000 people and displaced more than 2 million in a seven-year insurgency aimed at creating a state adhering to strict Islamic laws.

It controlled a swathe of land in northeast Nigeria around the size of Belgium at the end of 2014 but was pushed out by [U.S.-assisted] Nigerian troops, aided by soldiers from neighboring countries, early last year.