Since 2010, BOKO HARAM have been blamed for the killings of more than 1,700 people, according to a count by The Associated Press.
Yet,these militants are always threatening to do more and even face anyone.
In the video received by journalists Monday, Shekau brushes off any gains asserted by the security forces.
"You soldiers have claimed that you are powerful, that we have been defeated, that we are mad people," Shekau says, speaking in the local Hausa language. "But how can a mad man successfully coordinate recent attacks in Gamboru, in Malam Fatori, slaughter people inBiu, kill in Gwoza and in Bama, where soldiers fled underour heavy fire power?
"We have killed countless soldiers and we are going to kill more."
He further insists the extremists' "strength and firepower has surpassed that of Nigeria. ... We can now comfortably confront the United States of America."
Shekau also said Nigeria's military is "lying to the world"about its casualties. "They lied that they have killed our members, but we are the ones that have killed the soldiers."
He apparently was referring to Aug. 4 attacks on a military base at Malam Fatori and a police outpost in Bama, both near the border with Cameroon.