(ABC NEWS) -- Not only is it legal in America to transport unloaded, cased and locked firearms as checked luggage on airlines, but to the dismay of airport security officers it is also legal to carry a loaded weapon into 11 of the top 20 major airports including Los Angeles, Atlanta, Phoenix and Las Vegas -- which all have had incidents, as ABC News has found.
The killing of five travelers inside a Florida airport last week allegedly by a man who legally transported a handgun from Alaska in his checked luggage has renewed concerns over state laws that allow firearms to be carried into baggage claim and ticketing areas in half of the busiest U.S. airports.
While airport security has been significantly tightened since the Sept. 11, 2001, terrorist attacks, gun-friendly state laws nationwide allow law-abiding citizens to possess firearms in areas outside of the TSA passenger screening security bubble like the check-in lounge and baggage claim, even in major terminals.
In some instances, gun rights advocates carrying loaded AR-15 assault rifles through public areas of major American airports have caused a stir, despite having a legal right to openly carry their weapons.
Some airports allow only "open carry," while others require that weapons be concealed by individuals who hold state gun permits that are given to those who pass background checks.
Either way, it's a practice that doesn’t sit well with some lawmakers and law enforcement officials, particularly in the wake of violent attacks by terrorists last year at airports in Brussels and Istanbul, and on Friday by a gunman, Esteban Santiago, who was arrested in the fatal shootings at Fort Lauderdale-Hollywood International Airport.
"As with much about guns in America, the scandal is what is legal," said Mark Glaze, a gun control activist and former executive director of Mayors Against Illegal Guns. "Airports are filled with security personnel trained in the use of firearms, so the idea that an armed and untrained person with a gun is going to reduce the death toll is a fantasy."
For critics, the concerns boil down to: How do you distinguish between a terrorist or a deranged gunman out to inflict mass casualties, and a gun rights activist like those who have walked around with loaded rifles in airports in Georgia, Arizona, Nevada and Oregon in recent years? And why allow what amounts to self-deputized, armed citizens to walk around airports where security is equal to or greater than any other public space?
Inside the senior levels of federal law enforcement and aviation security, opinions vary about state laws that allow firearms to be carried in non-secure areas outside of the TSA security bubble like baggage claims and ticket counters.
“In the interest of public safety, this defies common sense,” one federal law enforcement official told ABC News.
But on the contrary, argues a former senior U.S. official, who oversaw federal security at many major U.S. airports, “It would be great if people were carrying legally in the non-sterile areas. It would be a deterrent."
"Can you imagine some idiot trying to do in Phoenix Sky Harbor Airport what we saw in Fort Lauderdale, when there's a bunch of Arizonans walking around with holstered handguns plainly visible? No way would someone attempt an attack," the former official said.
The current and former officials requested anonymity in order to speak candidly.
In some cases the debate has come down to what is perceived to be safer: to carry a concealed firearm or openly carry once inside an airport.
In Nevada, for instance, gun owners can open carry at airports but are not allowed to have a concealed weapon there even if they hold a state permit.
Two years ago, state legislators considered changing that by lifting a ban on carrying concealed guns in airports such as McCarran International Airport in Las Vegas, where 43 million travelers pass through each year.
Local officials said they opposed the move, as did major airlines.
"The consensus from the law enforcement agencies that work in and with the airport is that they would rather know who has a weapon coming into the terminal building," Rosemary Vassiliadis, the director of aviation in Clark County, who oversees McCarran, told the state senate's judiciary committee in March 2015.
"The presence of concealed weapons in airports makes it difficult for law enforcement to identify armed suspects during an active shooting," she said.
Interestingly, some lawmakers didn’t even realize it was legal to bring a gun to the airport.
"Before I took a look at this area of the law in preparation for this hearing, I had assumed that weapons were not allowed," said the committee's chair at the time, Greg Bower, a Reno Republican who now works as an FBI counsel.
The proposed Nevada law did not move out of committee.
Although there had been no reported incidents of anyone carrying firearms openly in McCarran for many years, a man entered the airport twice last spring carrying an AR-15 while picking up and dropping off passengers, an airport official told ABC News.
Law enforcement officials suspected that the man – who wasn't detained – had been affiliated with anti-government activists facing trial last year after standoffs on federal land and that he did not pose an immediate threat to travelers.
Then, last fall, an estranged husband, Jeffrey K. Brown, 68, was charged with shooting and wounding his wife and a man she was with while they walked to a car in a long-term parking at McCarran.
Gun advocates like Jerry Henry, executive director of GeorgiaCarry.org, defends the state laws, telling ABC News: “I carry a gun to protect myself from some bad person who might do me some harm. I think I should have the right to defend myself anywhere I go.”
He, like many others, argue that only law-abiding citizens would adhere to a gun ban in the public spaces of airports, leaving them vulnerable to the bad guys who ignore such restrictions – which is what law enforcement officials say Santiago did last week when he removed a handgun from his checked luggage after retrieving it in baggage claim and then opened fire.
The Ft. Lauderdale-Hollywood International Airport prohibits the carrying of guns in non-secure areas of the airport. Florida lawmakers had been considering a bill to repeal those restrictions days before the shootings.
While some have questioned whether guns should be completely banned from U.S. flights – even though they must be locked, and declared to the TSA and the airline – doing so would could prevent or severely complicate travel for law-abiding sportsmen and permit holders who wish to participate in hunting holidays and other recreational activities.
"Unsecured areas of an airport are exactly what their name states – unsecured,” says Jennifer Baker, a spokesperson for the National Rifle Association. “And law-abiding concealed carry permit holders are exactly that – law-abiding. Their right to self-defense should not be taken away simply because they choose to say goodbye or greet a family member in an airport lobby.”
But Joshua Horwitz, who leads the Coalition to Stop Gun Violence, said that "unsecured" areas are patrolled by police who have at times been faced with a split-second decision about whether a person exercising their gun rights poses a terrorist or criminal threat.
"It puts law enforcement in an untenable position," Horwitz said. "You need to make sure that the airport environment is secured. The trade-off [with allowing guns in airports] is to put law enforcement on the defensive."
Some states – such as Arizona and West Virginia – have passed "constitutional carry" laws which allow anyone to carry a firearm in public either openly or concealed without a state permit and background check.
While airport authority police in Tucson, Arizona have told ABC News that they will observe but won't stop anyone who carries a firearm in a non-threatening manner inside the non-sterile areas of the terminal, police two hours up the highway in Phoenix say they will likely detain anyone who carries a gun into Sky Harbor airport – for scaring people.
That's what happened to controversial Phoenix brain researcher Peter Steinmetz in 2014, when he walked into the airport there with a loaded AR-15 as a political protest in support of gun rights. He was quickly arrested but not charged and says his arrest record is in the process of being expunged.
"The recent tragic events in Fort Lauderdale unfortunately illustrate the danger of creating victim disarmament zones where otherwise law-abiding citizens are prevented from being able to defend themselves," Steinmetz told ABC News on Sunday. "Sky Harbor airport is a safer and freer place because it does not attempt to disarm citizens who are passing through the pre-screening portions of the airport."
Rafi Ron, former security chief at Ben Gurion Airport in Tel Aviv, Israel – often regarded as the gold standard for airport security – disagrees, arguing that, “There’s no room for private guns at the airport. On the other hand, I do understand the argument that some people are making. The public sees parts of the airport that are widely neglected as far as security is concerned."
“It certainly would be chaotic, and I don’t want to think what would happen if one bad guy would start to shoot and 20 good guys started shooting each other,” says Ron, a founding partner of New Age Security Solutions (NASS) based in Northern Virginia.
He added that security officers at the airport might end up shooting the good guys, mistaking them for an attacker.
Ron and others oppose expanding the screening to airport entrances, arguing that it would leave more people exposed outside to a possible attack. He suggested that U.S. airports need to have a greater security presence in non-secure areas, particularly in light of the attacks in Brussels, Istanbul and Fort Lauderdale. He also says that better trained security officers should be stationed there to spot suspicious behavior. The non-secure areas are controlled by local authorities.
John S. Pistole, the former head of the Transportation Security Administration from 2010 to 2014, said he opposes the idea of guns in public spaces at airports, but added that while he was at the helm of the agency, Congress had little appetite to challenge the gun-rights groups and pass federal legislation for all airports.
“I think most legislators are reluctant to do something nationwide because of the NRA,” said Pistole, who is currently president of Anderson University in Indiana. Passing a federal gun ban law for airports, he adds, “is just a huge political lift.”
There have been a number of other nonviolent incidents which still raised concerns about legally carrying in airports.
One occurred in Atlanta in June 2015, when gun rights advocate Jim Cooley dropped off his Chicago-bound daughter at the Hartsfield-Jackson Airport and accompanied her inside the non-secure area with a loaded AR-15 semi-automatic rifle slung over his shoulder.
He posted his appearance on YouTube, and the video went viral. No one was harmed but frightened people in the airport called police, who responded and filled out a report but were unable to do anything more than that.
In the YouTube video, an airport security officer is seen confronting Cooley and tells him that “calls are coming in left and right” about his weapon.
“People’s fear are not my responsibility,” Cooley tells the officer.
The high-profile prance through the airport came a year after the Republican-controlled Georgia legislature passed the Safe Carry Protection Act, which gave gun rights activist greater access to public spaces and allowed someone who mistakenly brings a gun to a TSA security checkpoint to retreat with the weapon without arrest and take it home or put in the car.
Republican State Rep. Rick Jasperse of Georgia, who sponsored the bill, concedes – as have other gun rights advocates – that openly carrying the AR-15 at the airport was “over the top.”
However, he says “it showed it doesn’t really harm anything to let people exercise their Second Amendment rights.”
His Democratic colleague, state Rep. Mary Margaret Oliver, who has tried to push for gun control legislation, doesn’t see it that way when it comes to guns and airports.
“Yes, that’s disturbing to me,” she told ABC News last year. “Unfortunately we have the inability to have a rational discussion about gun safety and legislation in Georgia.”
In Washington, U.S. Rep. Hank Johnson (D-GA) in 2015 introduced legislation – dubbed the Airport Security Act of 2015 – that would ban guns anywhere in airports except for law enforcement. It was the third time he’d introduced similar legislation, the first time being in 2010.
The legislation has gone nowhere.
“It’s clear in the aftermath of the Brussels attack and other recent incidents of guns in U.S. airports – including at LAX and here in Atlanta’s Hartsfield-Jackson – that we need to tighten up security at pickup and drop-off zones outside airports and in areas inside airports currently not covered by the TSA, including the baggage claim areas, ticket counters and lobbies,” Johnson said in a statement to ABC News.
Just how vulnerable non-secure areas of U.S. airports are was demonstrated during incidents at Los Angeles International Airport in recent years.
On July 4, 2002, Hesham Mohamed Hadayet, 41, an Egyptian national, opened fire at LAX at the ticket counter of El Al airlines, killing two people and wounding four others.
On Nov. 1, 2013, Paul Anthony Ciancia, 23, walked into Terminal 3 and opened fire, killing a TSA officer and wounding several others.
It’s unclear, however, if tougher gun laws or better security would have prevented those episodes of violence.
In November, in Oklahoma City, a former Southwest Airlines employee shot and killed Michael Winchester – who worked at the airline – in the parking lot of the Will Rogers World Airport. The shooter, Lloyd Dean Buie, 45, then shot himself.
Outside the United States, there have been instances of violence in the non-sterile areas of major airports.
Last March, 16 were killed in an ISIS attack on the international terminal in Brussels, Belgium.
In June of this year, a gun and bomb attack at the Ataturk Airport in Istanbul resulted in 45 deaths and hundreds injured.
Michael Bouchard, former assistant director the Bureau of Alcohol, Tobacco, Firearms and Explosives and a security expert, understands the argument put forth by gun rights activists. But, he says: “The only reason to carry is to draw attention and to get people wound up. There’s no other reason to carry an assault rifle.”
Ladd Everett, director of One Pulse for America, a gun violence prevention group, said there’s no reason to bring a gun to the airport.
“It’s hard to fathom why anyone would need to bring a loaded gun to an airport particularly given the level of security at the airport. It’s another one of those things that that is really turning gun-toters into super citizens who have more rights than the rest of us, and it’s offensive,” he said.
Allan Lengel, an ABC News contributor, spent nearly two decades covering federal law enforcement, including the FBI and Justice Department, for the Detroit News and Washington Post. He currently edits and reports for “Ticklethewire.com,” covering national security and law enforcement.
ABC News’ James Gordon Meek is National Security Investigative Producer in Washington.