I’ve written here before about some of the far-flung ramifications of the civil war in Syria spinning out of control. For example, Poles last month speculated that terrorists and militants holding European passports returning from Syria could strike soft targets across the Schengen Zone, those countries in Europe who have dismantled their customs and border checks effectively meaning entrance to one is entrance to them all. The result of that, of course, would be the end of the Schengen agreement and the return of passport checks at national borders.

Alas, the threat of European citizen terrorists will not be limited to Europe. Today, security has been ramped up for international flights heading to the United States because of credible threats of new terrorism using explosives not readily detectable by current screening technologies. The Syrian conflict is exacerbating the problem: Recently, a British citizen who has joined the Islamic State of Iraq and al-Sham has posted a video bragging about the explosives training he has received in Syria and boasted that he would soon bring that know-how home.

Airlines are doing the usual ramping up of screenings and interviewing passengers, and press reports also suggest that American officials will fly to European airports to supervise screening of passengers and baggage.

If the threat is increasingly not only the potential for harder-to-detect explosives, but also the passport holders who might carry them, perhaps it’s time to bite the bullet and eliminate visa waivers. That would result in reciprocal action by mainly European countries like the United Kingdom, France, and Germany.

More here.