How secure are our airports?

)Friday's shooting at Fort Lauderdale-Hollywood International Airport is yet another reminder that random acts of violence are exactly that -- random, unpredictable in where they will occur, when they will occur, and are perpetrated for a variety of reasons.

But with five people dead and several others injured, there are understandably numerous questions that law enforcement officers, the Department of Homeland Security and travelers in general will now be asking.

Sheldon Jacobson

As we saw in last year's terrorist attack in Brussels, the "soft bellies" of airports can become vulnerable targets. Why describe them as soft bellies? After all, aviation security checkpoints aimed at preventing terror attacks have created an increasingly secure airspace. The problem is, the law of unintended consequences has meant perpetrators have shifted away from attacking airplanes in flight in favor of areas like departure and arrival halls.

These so-called landside areas of airports are attractive to those intent on causing harm because they concentrate a large number of people in a relative small area, areas that are difficult to protect without creating a massive inconvenience to travelers.

Some suggest that the screening process could be pushed farther out, away from the check-in areas. But this would be unlikely to solve the problem, since it only shifts the vulnerability to another location. Meanwhile, the cost of such changes would also be prohibitive.

And, in the case of Friday's shooting, it appears that such a move would have done nothing to prevent the attack. In this case, the suspect is believed to have already had the firearm with him in his checked baggage, having apparently followed standard and lawful protocols by checking his firearm when he departed Anchorage, and picking it up again when he arrived.

Witness: Laptop stopped bullet from hitting me 02:18

Of course, regardless of the circumstances under which the shooter was able to access a firearm, the result among travelers is the same: an increase in social anxiety around air travel, and greater concern over aviation security.

Indeed, a shooting at one airport inevitably draws attention to the 400+ commercial airports across the United States, all while sparking concern over where and when the next such event might occur. If attention-seeking is the objective of a shooter, then airports will therefore continue to be high on the target list.

Despite all this, the data shows that mass shootings at airports are still extremely rare and are merely one target of gunmen -- nightclubs, malls, movie theaters and schools have all been targeted in the past few years. Despite the particular attention that tends to be paid to airport shootings, any locations with a high density of people who have freedom of movement are potential targets.

It is, so far, unclear why this shooter chose an airport rather than any other target, although with the suspect in custody, law enforcement might be able to gather some valuable insights that could help them prepare for future attacks. The problem they face, of course, is that lone-wolf attackers (if that is what the suspect is shown to be) are by their nature difficult to predict and stop. As a result, they will remain a continuing and significant threat.

Was the suspect in Friday's shooting, named by officials as Esteban Santiago, a lone-wolf terrorist? It is too early to know that. But it is already clear that the issue of people carrying firearms in checked luggage will become a heated topic of conversation among security officials, as well as those on both sides of the gun control debate.

And security officials will no doubt be investigating whether there was any evidence to suggest that the shooter should not have been permitted to fly at all.

Sadly, though, whatever the results of the investigation, we can already be sure that this won't be the last mass shooting in 2017. From 2006 to mid-2015, for example, a mass killing has occurred on average approximately once every 12 days in the United States, with mass killings defined by the FBI as an event in which four or more victims are killed.

Most of those shootings won't attract the widespread national attention seen Friday. But when innocent, random bystanders become victims of a mass shooting at an airport, it instills a certain kind of fear. Yes, everyone knows that more people die every day on America's roads than do in mass shootings. But no matter how many people are killed, these incidents spark debate over how best to prevent this type of event in the future.

These kinds of deliberate, random killings prompt a visceral reaction that connects us all. And that is one reason why airports will continue to remain targets.