The Mall of America has joined with the Department of Homeland Security in an anti-terrorism publicity campaign.
Shoppers will soon see posters and short videos with the message "if you see something, say something."
A New York ad executive thought up the slogan after the Sept. 11 attacks, and in recent years Homeland Security began using it.
Mall officials say the effort is not a response to any particular threat, nor is it a reaction to the attempted bombing in Portland.
But security director Doug Reynolds said his 150 officers can't be everywhere at once in the nation's largest mall.
"If you can enlist the assistance of others, that 40 million that are coming through a year, visiting the mall and get them out there looking at what's going on, I think you have a higher success rate," he said.
The Mall of America says it's the first private retail establishment to join the "see something, say something" campaign.