The Mall of America has beefed up security and Homeland Security Secretary Jeh Johnson is urging shoppers there to be "particularly careful" in the wake of a terror threat yesterday, reports CNN. "There will be enhanced security there, but public vigilance, public awareness and public caution in situations like this is particularly important, and it's the environment we're in, frankly," Johnson said this morning on State of the Union. His comments came after al-Shabab yesterday released a video in which a militant referenced the 2013 attack on a Kenya mall, then asked, "What if such an attack were to occur in the Mall of America in Minnesota?" A security spokesman tells the Minneapolis Star-Tribune that the mall has "implemented extra security precautions. Some may be noticeable to guests and others won’t be." CNN notes that al-Shabab has recruited heavily in the Minneapolis area. (More Mall of America stories.)