The group, which has ties to Al-Qaeda, took

After a recent terror threat on an American mall, an official has revealed that the United States' Federal Bureau of Investigation has been staging mock attacks in U.S. shopping centers for nearly two years to test their readiness.

The secretary of Homeland Security Jeh Johnson recently warned shoppers at Minnesota's Mall of America to remain vigilant after a new terrorist video from Al-Shabaab -- An Al-Qaeda-linked militant group out of Somalia -- threatened an attack on the iconic mall.

But, an official told CNN that the FBI has been preparing for such an attack for nearly two years, since the militant group led a siege at a Kenyan mall, resulting in more than 60 deaths, CNN reports.

SWAT: An official has revealed that the United States' FBI has been staging mock attacks in U.S. shopping centers for nearly two years to test the readiness of SWAT teams (stock image)

Mall of America: A video released Saturday, reportedly by the Somalia-based militant group Al-Shabaab, threatened a terror attack on Minnesota's Mall of America as well as malls in Canada and the UK

A law enforcement official said that the FBI has teamed up with various malls across the country staging the fake attacks during off hours to test the readiness of SWAT teams.

The Department says there is no specific, credible plot from Al-Shabaab, but since the recent release of a video, reportedly by the group, threatening an attack, the Mall of America has heightened its security, USA Today reports.

Vigilant: The secretary of Homeland Security Jeh Johnson (photographed) recently warned shoppers at Minnesota's Mall of America to remain vigilant

The official told CNN that in light of the attack on Westgate mall in Nairobi, the FBI has worked to improve security and said that, since then, the FBI has implemented a program working with U.S. malls in order to do so.

In the terrorist video released online Saturday, a hooded man, wearing fatigues spoke of the Westgate attack and called for similar attacks on the Mall of America, the country's largest mall, as well as malls in Canada, and the United Kingdom, according to USA Today.

'What if such an attack was to occur in the Mall of America in Minnesota? Or the West Edmonton Mall in Canada? Or in London's Oxford Street?' the man says.

Al-Shabaab was named a terrorist organization by the U.S. Bureau of Counterterrorism in 2008 and pledged its allegiance to Al-Qaeda in 2012.

The Somalia-based group has limited its attacks to Kenya, Uganda, and its home country, but U.S. officials say the group may be feeling left out as the Islamic State makes headlines, CNN reports.

Both the FBI and the Department say they believe the video is a call to action to those who have been radicalized as well as an effort to compete for attention and recruits with other militant groups.

Christopher Voss, FBI former agent and terrorism expert, told FOX News that Al-Shabaab's video was a 'guilt trip' to 'try to increase funds.'

'They're low on money,' Voss said.

Westgate: The militant group took responsibility for the 2013 attack on Nairobi's Westgate mall where more than 60 people were killed (photographed)

'They needed to do an announcement to make their followers --who are in the area of [Mall of America] and are not doing anything --make them feel guilty for sitting on their hands...they're trying to get them to send them more money.'

Johnson told CNN that government officials are taking this threat, just as they would any other, very seriously, no matter what the terrorist group's motives are.