And for good reason, and not just because of copycats.  The Daily Beast’s Miranda Green writes that American retail centers have tightened security and begun reviewing their resources in the wake of a terrorist attack by Somalia terror group al-Shabaab on an upscale Nairobi mall over the last several days:

The Department of Homeland Security is urging shopping malls in the United States to increase security in the aftermath of the carnage wrought by al Qaeda’s Somalia affiliate over the weekend in Nairobi, Kenya.

Malachy Kavanagh, a spokesman for the International Council of Shopping Centers, told The Daily Beast on Monday that the department contacted shopping malls on Sunday to check on the precautions they were taking against mass shooters.

U.S. intelligence officials say there is no specific threat information suggesting al Qaeda is planning a similar kind of mass shooting in American shopping malls. Nonetheless, security experts worry about copycats.

It’s not just the copycats that have American officials worried. Shabaab has successfully recruited dozens of young men from the US, mostly from the Twin Cities and its large Somali ex-pat community here. CBS News reviewed the well-known problem last night, noting that as many as 60 have disappeared over the last few years, and are presumed to be part of the terror group. Their familiarity with the US would make it easy for them to infiltrate to conduct a terrorist attack here, perhaps using the same model as Nairobi or Mumbai:

It’s an ongoing problem, and the FBI and local community have cooperated with each other to try to stop it. That leaves one particular mall as a potential target — the nearby Mall of America, which is the largest in the US and attracts considerable international business:

The Mall of America, the biggest shopping mall in the United States, has already increased security measures in response to the Nairobi mall siege over the weekend.

“Mall of America continues to monitor the tragic events unfolding in Kenya with the help of federal, state, and local law enforcement agencies,” said a spokesman for the mall. “Mall of America has implemented extra security precautions. Some may be noticeable to guests, and others won’t be. We will continue to follow the situation, along with law enforcement, and will remain vigilant as we always do in similar situations.”

The giant shopping mall is in Bloomington, Minnesota, less than 20 minutes from Minneapolis, which boasts a vibrant Somali-American community, from which al Qaeda’s Somalia affiliate, Al-Shabab, has been recruiting heavily.

One possible problem for that mall as a target would be the risk of exposure for the infiltrated Shabaab terrorists. They run a higher risk of being recognized in the Twin Cities than they would in other parts of the country.  As MoA states, though, they can’t run the risk of assuming that will be the case.

One potential step malls might take to beef up the deterrence factor would be to welcome lawfully armed citizens to shop there.  The Daily Mail reported yesterday that one such man in the Nairobi attack managed to save perhaps as many as 100 potential victims of the siege:

A former marine emerged as a hero of the Nairobi siege yesterday after he was credited with saving up to 100 lives.

The ex soldier was having coffee at the Westgate mall when it was attacked by Islamists on Saturday.

With a gun tucked into his waistband, he was pictured helping two women from the complex. …

The former soldier is said to have returned to the building on a dozen occasions, despite intense gunfire.

A friend in Nairobi said: ‘What he did was so heroic. He was having coffee with friends when it happened.

‘He went back in 12 times and saved 100 people. Imagine going back in when you knew what was going on inside.’

Sources said the soldier was in the Royal Marine and now lives in Kenyan. He cannot be named for security reasons.

The Mall of America declared itself a “gun free zone” in response to the expansion of carry permits in Minnesota.  Maybe they should rethink that policy in light of recent events.