Professor Jytte Klausen, who teaches at Harvard and Brandeis Universities, and is the founder of the Western Jihadism Project, says European Union countries have provided the Turkish authorities with a list of 10,000 names of people, suspected of being ISIL sympathisers and ones to watch out for.
According to Professor Jytte Klausen:
"The Turks complained that they can't do it, and you know what, they can't. It's a capacity busting proposition, to watch out for 10,000 westerners."
"They are not going to be able to check most names on that list of 10,000."
"Only if there is a case where there is an urgent bulletin out, because it has been discovered that they had left — and the urgent bulletin would be on the top of the desk — that's when you can catch people as happened here," said Klausen.
The problem, according to Professor Klausen, is that "getting on a plane is subject to far less scrutiny than getting off a plane". Klausen described the indirect routes that are increasingly taken by would-be jihadists.
Kids need to stop running away to join terror groups. It'll only make it harder at airports for teenagers like me who travel a lot. #ISIS— Abdikarim Hussein (@Abdikarim_Abdi3) March 16, 2015
Due to gaps in intelligence sharing, travelling through another country makes it easier to arrive undetected.
"There is not comprehensive data sharing among the European Union countries with respect to people who are merely suspected of doing something."
"Therefore you have airports like Gatwick, and other European airports, that have a lot of discount airlines flying out," Klausen said.
With so many teenagers trying to join ISIS, hopefully their new plan of attack will be reduced to 'giving dirty looks'?— Craig Deeley (@craiguito) March 16, 2015
Meanwhile, three British teenagers who recently flew to Turkey to join Islamic State in Syria were detained by Turkish officials and flown back to the UK where they were arrested on suspicion of preparing acts of terrorism.
The two 17-year-olds and a 19-year-old from North West London have been bailed.
According to the Times, Scotland Yard received a tip-off from the younger teenager's parents when they did not return home from their Friday prayers. The police then alerted the Turkish officials.
If we think teenagers can be easily "groomed" to join ISIS as "victims", we might want to pause before reducing the voting age to 16.— Mark Littlewood (@MarkJLittlewood) March 15, 2015
"Officers alerted the Turkish authorities who were able to intercept all three males, preventing travel to Syria", a police spokesperson said.
They arrived back in Britain on Saturday night where counter-terrorism officers arrested them.
The three teenagers had flown to Turkey from Barcelona, Spain. The two 17-year-olds were stopped at Istanbul's Sabiha Goken airport by Turkish authorities. The 19-year-old was only detained after being questioned by the police in Turkey.
Officials in Turkey say, "This is a good and clear example of how the security cooperation between Western intelligence agencies and Turkey should work".
Meanwhile, another teenager has been arrested in the UK on suspicion of preparing to travel to Syria to join militant group, Islamic State. West Midlands Police say the 18 year old from Birmingham was arrested at his home in a pre-planned and intelligence led operation.