US vows to track down IS leaders

The United States vowed Monday that it would track down and defeat surviving leaders of the Islamic State movement after its elusive supremo Abu Bakr al-Baghdadi appeared to speak in a newly released videotape.

The US-led coalition against the group will fight across the world to "ensure an enduring defeat of these terrorists and that any leaders who remain are delivered the justice that they deserve," a State Department spokesman said.

In Baghdadi's first purported appearance in five years, a cross-legged speaker said to be the world's most wanted man referred to the group's defeat last month in its final redoubt of Baghouz and threatened revenge attacks.