An international expert on airport security says that until security forces develop the ability to react to terrorists within seconds, airports will remain vulnerable to attacks like those in Istanbul and Brussels.
"If you look at the tactics used by the terrorists in Istanbul, they started by shooting. If the response would have come in a matter of seconds and was effective enough, they probably would have been dead before they detonated their devices and before they managed to cause a large number of casualties," said Rafi Ron, a former security chief at Tel Aviv Ben Gurion International Airport who now works as an airport security consultant in the United States and other countries.
Ron declined to say whether that response would come in the form of police snipers, SWAT teams or other means.
"I really don't want to get into the technical detail. I don't think we should be discussing the defensive tactics," he said. "There's more than one way to respond in a matter of seconds."
Ron points out that airports are familiar terrorism targets, with an explosion that killed and injured dozens in Moscow five years ago and the attacks in Vienna, Paris and Rome in the 1970s.
"There is a lot that can be done," said Ron, who was instrumental in setting up the current security system in Tel Aviv. "It's not a common practice in most of the Western world. It is more common in the areas that are identified as high-risk areas. Certainly, at airports in war zones, I assume these types of measures are happening."
At Baghdad International Airport, civilian cars are not allowed to drive to the terminal. Passengers must transfer to approved buses or taxis at a parking lot at the perimeter of the airport, after which they pass through two screening checks, including one with sniffer dogs, before reaching the terminal. Inside the terminal, there are two more X-ray machines prior to check-in, another after immigration, and a final one at the gate.
So far, Baghdad has avoided a major attack on its airport during the country's war against the Islamic State. But in November 2014, a suicide car bomber detonated explosives at the checkpoint at the entrance to the public parking lot on the airport's outskirts, injuring five people.
Israel's aviation security - at Tel Aviv and on flights from abroad that are departing for Israel - is among the tightest in the world.
Several kilometres before travelers arrive at the main terminals of Ben Gurion airport, they first pass through a military checkpoint, where the identities of taxi drivers and passengers can be scrutinized. Travelers whom guards deem suspicious can be questioned and their baggage searched several miles from the terminals.
Israeli authorities freely acknowledge that they profile passengers. Young Muslim men, including from the United States, are often subjected to second and third screenings - including strip searches and examinations of their personal electronic devices.
At the airport terminal, other guards may stop and question passengers before they are allowed entry. At check-in, there are more questions by security officers: Whom do you know in Israel? What are their names?
But in Europe, the United States and other regions, passengers and others have easier access to airports.
After the terrorist attacks in Brussels, where a bomb was detonated in the terminal area before the security checkpoint, questions were raised in Britain over where the ring of security should be placed at an airport and whether the existing security arrangements were enough to prevent attacks. As in Brussels, passengers entering airport terminals in Britain do not immediately go through security checks.
At U.S. airports, security responsibility is shared by the Transportation Security Administration and local law enforcement agencies.
"You have to look at the division of responsibility between the federal government and the local government, when the feds consider themselves responsible for passengers and bags, and they expect that local government will protect the airport facility," Ron said. "In most cases, those police forces are too few, too thin and hardly present at the right place in the airport, and, in any case, too busy issuing traffic tickets rather than getting involved in the protective missions at the airport."
Most airport law enforcement officers lack the "combat skills to do what is required to meet this type of challenge," he said.
"We have to reconsider our strategy on this [because] of the latest attacks in Brussels and in Istanbul," he said. "We have to adjust our existing resources as a way of mitigating this type of risk at this time."
"If you look at the airports that serve Washington, D.C., and ask yourself the question, how long would it take for somebody to actually respond to an active shooter, and you won't be able to avoid the conclusion that the situation would be much worse than the one in Istanbul."