NAIROBI, Kenya — An Islamic insurgent group that controls much of lawless Somalia has released a video showing its members vowing allegiance to Osama bin Laden, training in dusty camps and slamming Somalia’s U.S.- backed president as a traitor.

The tape was released late Sunday by al-Shabab, an insurgent group that last week hit the African Union peacekeeping base with suicide car bombs, killing 21 people.

Sheik Hassan Ya’qub, a spokesman for al-Shabab, said the video is “aimed at showing how the youth are well trained and ready to defend their holy land.” Shabab means “youth” in Arabic.