Mall Threat 'Not Likely' to Inspire Attacks Soon, Feds Say, But Malls Prepare for Worst

— -- With groups like ISIS flooding the Internet with its propaganda, a weekend call for attacks on U.S. shopping centers by a lesser-known terrorist group in Somalia is "not likely" to inspire violence anytime soon, according to federal authorities.

In a 76-minute propaganda video posted online Saturday, the al Qaeda-linked group al-Shabab urged Western followers to strike in their home countries with attacks like the one targeting a popular mall in Kenya two years ago, when a four-day siege tied to al-Shabab left 67 dead.

The video posted Saturday specifically mentioned the Mall of America in Bloomington, Minnesota, as a possible target, prompting the massive shopping center to conduct two drills Monday.

"Our top priority at Mall of America is the safety of all guests. These test drills help us to prepare for emergency situations," signs posted in the mall reportedly read.

U.S. officials expressed skepticism that al-Shabab's video will produce an emergency situation.

"Our view is it's propaganda," State Department spokeswoman Jen Psaki said of the video. "There's not a credible threat against malls."

Similarly, the FBI and Department of Homeland Security said Sunday that so-called "homegrown violent extremists" are "not likely to respond immediately" to the weekend call for attacks because such homegrown radicals are paying "greater attention ... to supporting fighters in other foreign conflict zones, such as Syria," where ISIS is wreaking havoc and using online social media to radicalize tens of thousands around the world.

In addition, al-Shabab's past messaging has had "limited resonance," the FBI and DHS said in an intelligence bulletin issued to law enforcement on Sunday.

"Previous al-Shabab videos have called for Western Muslims to conduct attacks around the world without result," and neither the 2013 attack on the Westgate mall in Nairobi, Kenya, nor al-Shabab's subsequent praise of it have "mobilize[d] operatives," the bulletin added.

Still, the top law enforcement agencies urge security officials and shoppers at malls across the United States to remain vigilant, saying the "individualized nature of the radicalization process makes it difficult" to predict or detect plotting by homegrown radicals.

During a morning drill at the Mall of America on Monday, a recording saying "Attention Guests: This a drill" echoed throughout the mall as shopkeepers temporarily brought gates down.

"We're concerned because, yes, it could happen," one shopper at the mall Monday told NNS. "It's a big target for someone that wants to cause a lot of havoc."

Still, the shopper said that is "not going to probably keeps us away."

Al-Shabab has proven to be a potent and lethal force in East Africa. Three years before the attack on Westgate mall in Kenya, the group claimed responsibility for a series of coordinated bombings in Uganda targeting soccer fans watching the 2010 World Cup. More than 70 people were killed, and another 70 were injured.

For several years, al-Shabab has been waging war against the fledgling government in Somalia, which has been backed by the U.S. government and the government in neighboring Ethiopia.

After Ethiopian forces moved into Somalia in 2007, al-Shabab was able to recruit dozens of Americans to the fight, as estimated by the U.S. Justice Department. But many of those Americans have said they went to Somalia to push the Ethiopians "invaders" out, not to harm the United States in any way.

Meanwhile, reports out of Somalia have indicated deep fractures within al-Shabab over whether the group should become more of a global enterprise and try to launch attacks outside East Africa, perhaps in the West.

"We assess al-Shabab is [still] focused primarily on efforts to topple the Somali Federal Government and expel foreign troops from Somalia,” the FBI and DHS said in the bulletin on Sunday.

In addition, DHS issued a separate statement to media on Sunday, saying: "As a general matter, we are not aware of any specific, credible plot against the Mall of America or any other domestic commercial shopping center."

Get real-time updates as this story unfolds. To start, just "star" this story in ABC News' phone app. Download ABC News for iPhone here or ABC News for Android here. To be notified about our live weekend digital reports, tap here.