WASHINGTON (AP) — Homeland Security Secretary Jeh Johnson says U.S. officials are taking seriously threats like the one in a video that's purportedly from a rebel group in Somalia with links to al-Qaida.

In the video, Muslims are urged to attack shopping malls in the U.S., Canada and other Western countries. The narrator specifically mentions the Mall of America in Minnesota and Canada's West Edmonton Mall.

Johnson tells CNN that groups like these are "relying more and more on independent actors to become inspired."

The extremist group al-Shabab again says in the video that its September 2013 attack on the Westgate Mall in Nairobi, Kenya, was in reprisal for Kenyan military involvement in Somalia.