 -- One of the largest malls in the United States has heightened security after a video claiming to be posted online by a Somali militant group affiliated with al Qaeda called for attacks against the mall.

The Mall of America in Bloomington, Minnesota, issued a statement Saturday, saying it had increased security in light of the video purportedly from al-Shabab, which took credit for the deadly attack at a Kenyan mall that killed at least 67 civilians in 2013.

Department of Homeland Security Secretary Jeh Johnson called the video the "new phase we’ve evolved in terms of the global terrorist threat and what we need to do in terms of counter-terrorism.."

"Groups like ISIL [ISIS], al-Shabab, AQAP (al Qaeda of the Arabian Peninsula) are now publicly calling for attacks either through the internet, through videos, through publications, which means that we need to respond militarily but we also have to have a whole government approach through law enforcement, homeland security and frankly countering violent extremism efforts here in the homeland in communities," Johnson said on ABC's "This Week." "We’re in a new phase now and I’m afraid that this most recent video release reflects that."

Matt Olsen, former director of the National Counterterrorism Center and current ABC News consultant, said despite al-Shabab not having a known ability to carry out such an attack in the U.S., the threat must still be considered.

"Over the past few years, al-Shabab has been degraded overall, but it is still active in Somalia and parts of East Africa," said Olsen. "al-Shabab has no known operational capacity in the U.S., and we haven't seen the group develop the ability to carry out a complex attack here. But this type of threat can't be discounted, and the FBI and local police departments will have to take appropriate steps in response."

The Department of Homeland Security and FBI issued a joint statement Sunday, saying the agencies were aware of the "reported call from al-Shabab for 'Westgate style' attacks against shopping centers around the world, to include in the United States."

"In recent months, the FBI and DHS have worked closely with our state and local public safety counterparts and members of the private sector, to include mall owners and operators, to prevent and mitigate these types of threats," the statement continued.

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