Kano - Boko Haram leader Abubakar Shekau vowed in a new video released on Monday that the group would defeat a regional force fighting the militants in the northeast, Niger and Cameroon.
"Your alliance will not achieve anything. Amass all your weapons and face us. We welcome you," he said in a 28-minute speech, one of three videos posted by the Islamists on YouTube.
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Troops have been joined by soldiers from Chad, Cameroon and Niger in recent weeks because of increased concerns about Boko Haram's threat to regional security.