The al Qaeda branch in Somalia released a video Saturday celebrating the September 2013 attack on the Westgate shopping mall in Nairobi, Kenya, that killed 60 people in a four-day siege. In the 66-minute video, unleashed on Twitter in both English and Arabic, al-Shabab called for attacks on specific targets in the U.S., Canada and Britain.

“If just a handful of mujahedeen [militant jihadists] fighters could bring Kenya to a complete standstill for nearly a week, just imagine what the dedicated mujahedeen could do in the West to American or Jewish shopping centers across the world,” a masked gunman says toward the end of the video. “What if such an attack were to occur in the Mall of America in Minnesota? Or the West Edmonton Mall in Canada? Or in London's Oxford Street?”

The video raises concern it could help inspire lone-wolf attacks by radicalized individuals in these countries who are teetering on committing violent acts in the name of Allah. Online social media has helped widen the audience for Islamist propaganda despite efforts by Facebook and Twitter to weed out troubling broadcasts.

While social media sites are filled with militant Islamist propaganda calls for violence (such as how to make bombs in your mother’s kitchen or praising the usefulness of Honda motorcycles to commit terrorist acts), it’s unusual for terrorists to be so specific about civilian targets. News of the video was first reported by Bethesda, Maryland, SITE Intelligence Group, which monitors activities of extremist groups.

"The English-speaking narrator in this video sounds remarkably similar to the narrator from past Shabab releases,” SITE Director Rita Katz said in a report announcing the news Saturday. Al-Shabab has released similar videos in the past, including one cheering the murder of British soldier Lee Rigby, who was killed May 22, 2013, by British citizens Michael Adebolajo and Michael Adebowale. In August, Muslim convert Brusthom Ziamani, 19, was arrested for allegedly plotting to behead a British soldier in a lone-wolf copycat attack inspired by the Rigby murder.

Al-Shabab (which means “the youth” in Arabic) claimed responsibility for the Friday suicide attacks in Mogadishu that killed at least 25 and wounded 40 at a hotel where government officials were meeting. Somalian President Hassan Sheik Mohamoud condemned the attack and pledged to continue to work for stability in the war-ravaged East African country.

Al-Shabab still maintains a strong presence in the country, however, and has staged numerous smaller attacks in the capital in recent months. A suicide car bomber Jan. 22 attacked a Mogadishu hotel where a group of Turkish officials were preparing for a state visit by Turkish President Recep Tayyip Erdogan. That attack killed three Somali civilians.