Asked about the specific threat against the Mall of America, Johnson said: "Any time a terrorist organization calls for an attack on a specific place we've got to take that seriously. What we're telling the public is you've got to be vigilant. ... There will be enhanced security there that will be apparent, but public vigilance, public awareness and public caution in situations like this is particularly important."
In the slickly produced video posted online, a masked man, his face wrapped in a black-and-white kaffiyeh-type scarf and wearing a camouflage jacket, declared: "Westgate was just the beginning." The video included footage from major news organizations showing the assault on the mall and said it was in reprisal for alleged abuses by Kenyan troops against Muslims in Somalia.
"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?" said the man, who spoke with a British accent and appeared to be of Somali origin.
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The Mall of America said in a statement that it was "aware of a threatening video which includes a mention and images of the mall," and said extra security had been put in place.
Minnesota Gov. Mark Dayton was monitoring the situation and has been in regular contact with the commissioner of the Minnesota Department of Public Safety which is coordinating with federal and local law enforcement agencies and the Mall of America "to assure the safety of all Minnesotans," said a statement released by the governor's press secretary Matt Swenson.
Shoppers seemed undeterred Sunday by the threat.
"I'm more afraid of the cold today than any terrorists," said Mary Lamminen, of St. Paul.
David Modrynski said he talked with his wife and son about whether to visit the mall after hearing about the video. "But we can't stop living our lives because somebody says they're going to do something," Modrynski said.
While al-Shabab has carried out attacks in neighboring Kenya, Uganda and Djibouti, which all have troops fighting the extremists as part of the multinational African Union force, the al-Qaida affiliate has never operated outside East Africa and the Horn of Africa.
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