Recent research shows that the number of foreign fighters joining armed groups in Syria and Iraq has doubled, indicating that despite efforts to diminish the flow a large number are still coming.
According to the New York-based security consultancy Soufan Group, the number of foreign fighters has surprisingly increased to between 27,000 and 31,000 people from 12,000 in 2014.
The number of countries from which people have traveled to join terrorist organisations such as DAESH has also increased.
"Despite sustained international effort to contain the Islamic State [DAESH] and stem the flow of militants travelling to Syria, the number of foreign fighters has more than doubled," Richard Barrett, a Soufan Group employee and former head of global counter-terrorism at Britain's Secret Intelligence Service (MI6), told Reuters.
The armed groups attracts fighters from country's such as Norway to Uzbekistan, with an increasing number coming from the Middle East, North Africa and the former Soviet Union.
Some 6,000 fighters have come from Tunisia to Syria, 2,500 from Saudi Arabia and 2,400 from Russia. Barrett reports that around 3,700 fighters come from France, Britain, Germany and Belgium.
"As the Islamic State [DAESH] changes its focus from consolidating control of territory to attacking its foreign enemies in their own homelands, or their interests elsewhere, the profile of its foreign recruits will also change," Barrett said.
"The Syrian civil war will not end soon," he added.
Recruitment to armed groups
The foreign fighters who decide to join certain armed groups are recruited in different ways. Many are recruited through social media.
Soufan told Reuters there is a "personal nature of recruitment" and "it appears more often to prepare the ground for persuasion, rather than to force the decision," so the fighters join willingly.
"Recruitment through social media becomes less important than via direct human contact, as clusters of friends and neighbors persuade each other to travel separately or together to join the Islamic State [DAESH]," he added.
The DAESH terrorist group has claimed responsibility for several attacks, such as the Paris attacks on November 13 that left 130 people dead.
Western intelligence officials say foreign fighters in Syria are a threat to the security of Western countries as through training they may become a threat and carry out several attacks in their home countries upon their return.
"Even if the Islamic State [DAESH] is a failing enterprise in steady decline, it will be able to influence the actions of its adherents, and it may become more dangerous as it dies," Barrett wrote.