There are currently an estimated 700 foreign fighters, European and Russian Muslims, engaged in fighting on the side of the opposition in Syria, according to a study carried out by the International Centre for the Study of Radicalisation. The total number estimated to have fought on the side of the Islamist opposition since 2011 is believed to be anywhere between 2,000 and 5,500 fighters. The breakdown is about 450 Europeans and 250 Russians. Then there are also an unknown number of Arabs who have joined the fight.
In the greater scope of things those numbers might seem relatively low -- 450 fighters. A proportion of those fighters will likely be killed. Additionally, studies have found that typically only about two percent of those who do volunteer to go fight and return to Europe become involved in terrorist activities. Still, two percent of 450 is nine.
The Boston Marathon bombers consisted of two men who kept the entire Boston area police forces and US federal agents occupied for nearly two days. Now imagine if they were nine of them.
The recent wars in Afghanistan and in Iraq have proven to be ideal breeding grounds for potential terrorism candidates and ideal recruiting grounds for the Islamists. Therefore there are good reasons to believe the trend will continue with Syria.
The attack on the Boston Marathon should serve as a reminder of the damage that a small but dedicated number of fanatics can cause to a major metropolitan area. At the same time the question needs to be asked why is the United States continuously on the receiving end of the Islamist's anger?
One quick answer is US foreign policy where many are those in the Middle East who feel that the US applies a different set of rules when it deals with Arab and Muslim countries.
Take for example the recent increase of pilotless drones, or Unmanned Aerial Vehicles (UAV) by the United States in Pakistan.
According to a detailed inventory kept by the Bureau of Investigative Journalism, a non-profit organization that keeps track of the use of UAVs, the US has killed 3,115 people in Pakistan using drones. Of those only 1.5 percent were regarded as "high profile targets." The rest were innocent bystanders, including 175 children. Otherwise known as "collateral damage."
In a tribal society where vengeance is passed down from generation to generation as though it were some precious family heirloom, it would be a mistake to brush this "collateral damage" under the rug. The unresolved crises in Syria and in Pakistan will have serious consequences down the road.
The numbers may seem small but the threat remains. Intelligence reports compiled with newspaper stories give the following figures of European Muslims who traveled to Syria to fight:
The Netherlands: 100 where the government raised its terrorism threat level to "substantial" based on worries that the individuals who are believed to have travelled to Syria - some may return and become involved in terrorist attacks.
Among those who fought in Afghanistan and Iraq returned to their countries of adoption they did so all the more hardened by the experience of having participated in violent warfare in the world's most inhospitable terrain, having fought against the world's best trained, best equipped and most formidable fighting machine in the history of mankind. Those who are fighting and who will fight in Syria will return after having faced a ruthless force where the horrors of war will have shown them scenes they possibly never imagined even in their worst nightmares.
Additionally, these hardened fighters return to uncertainty in their countries of adoption. With rising unemployment and skills they can hardly list on a CV, they remain easy prey of jihadi recruiters.
This is what happened in the aftermath of Afghanistan and Iraq. And this is what will happen post Syria. The current situation in Syria holds all the elements for the making of a perfect Islamist jihadi storm. There is a tragedy waiting to happen.
Claude Salhani, a specialist in conflict resolution, is an independent journalist, political analyst and author of several books on the region. His latest book, 'Islam Without a Veil,' is published by Potomac Books. He tweets @claudesalhani.