Hardly a day goes by without news or reports of jihadists of Arab or foreign nationality travelling to Syria to fight alongside the opposition against the regime of Syrian President Bashar Assad.
Many of those jihadists leave their home countries driven by religious or humanitarian conviction, expecting to join the battle against an oppressive regime.
However, some either arrive with an extremist agenda, or find extremist groups waiting to exploit them in a way reminiscent of how al-Qaeda used foreign recruits to plunge neighbouring Iraq into a bloodbath, all in the name of jihad.
In Iraq, Abu Musaab al-Zarqawi and his group, al-Qaeda in Iraq (AQI), succeeded in exploiting a stream of Arab jihadists, some of whom came to join what they viewed as a holy war against foreign troops and the new Iraqi government.
Al-Qaeda sent a number of them on missions to carry out suicide bombings that resounded across the media because they caused countless deaths, injuries and destruction.
Iraqi citizens saw people calling themselves "jihadists" -- who had allegedly come to defend Iraqis, not kill them -- gradually destroying their country and killing their countrymen in operations.
Over time, the jihadists' operations and their imposition of an extremist interpretation of sharia rule created a rift between them and Iraqi citizens, a rift that later led to al-Qaeda's expulsion from large swaths of the country on the part of citizens, Iraqi and foreign armed forces, and Sahwa forces.
In Syria, foreign jihadists are joining the fighting in this country, specifically in the ranks of Islamist groups that now number in the dozens. A number of these volunteers -- which some estimates put between1,000 to 5,000 fighters -- have joined the extremist group Jabhat al-Nusra (JAN).
According to a study by the counter terrorism think tank Quilliam, JAN is an AQI offshoot. Many suicide attacks carried out by JAN members resemble operations carried out by al-Qaeda.
Even though these bombings have yet to produce an end result in Syria similar to the one precipitated by al-Qaeda's operations in Iraq years ago, some indications have begun to surface that Syrian citizens opposed to the Assad regime do not approve of JAN.
Last week, for the third day running, civilian residents of al-Mayadeen city in Deir Ezzor province came out to protest the presence and control of JAN over their community, where JAN set up a religious police force and held a military parade, according to the Syrian Observatory for Human Rights.
For analysts and observers, JAN, which counts many foreign jihadists, including AQI members, in its ranks, is simply trying to revive the old Iraq formula.
"Jabhat al-Nusra is an extension of al-Qaeda's plan; it [recycled] al-Qaeda's old format, circa 2003 in the [Syrian] framework and revived it anew," former Libyan jihadist Noman Benotman told Al-Shorfa.
Al-Qaeda's entry into any struggle eliminates all other players, says Benotman.
"Wherever al-Qaeda set foot, there was no room for others," he said. "The entry of al-Qaeda and its strict ideological programme [into the country] would cause unnatural disaster. Syria urgently needs pluralism, even before democracy, and al-Qaeda does not accept such pluralism."
As was the case during al-Qaeda's time in Iraq under al-Zarqawi's leadership, various groups are calling fighters from around the world to jihad in Syria.
Last October, a UN commission investigating abuses in Syria said foreign fighters could contribute to an increased "radicalisation" of the conflict.
Commission head Paulo Sergio Pinheiro said the commission feared foreign combatants were not fighting to "build a democratic state in Syria" but "for their own agenda".
The commission said the fighters came from 11 countries, not only neighbouring countries.
Morocco's Al-Massae newspaper recently published a report on the recruitment of Moroccans to fight in Syria, some of whom have carried out suicide attacks. In August, a group calling itself Ansar al-Mujahedeen posted a video online showing a man preparing to attack a Syrian regular army encampment in Nayrab, near Aleppo. The newspaper reported that the man is a Moroccan named Rashid Wehbe, who holds a Spanish citizenship and resides in the Spanish city of Ceuta.
"Networks of Islamists saturated with jihadist ideology" are actively recruiting young Moroccans "to fight against the Syrian army and carry out suicide attacks", Al-Massae wrote, detailing an example of recruitment methods in a clothing market located between Fnideq and the Ceuta border point.
In this small market, well-planned recruitment operations are carried out with modern communication techniques and "a heavy dose of religious ideology that renders the recruits unable to think rationally, so they abandon everything in favour of an idea they believe in to the death", the newspaper said, providing examples.
The Tunisian media published similar reports on jihadist networks that recruit young men and send them to fight in Syria, a phenomenon that repeats in every Arab country, from Egypt and Libya to Jordan and Gulf countries like Yemen and Saudi Arabia.
In December 2012, AFP correspondents interviewed a number of foreign fighters in north-western Syria.
One AFP correspondent made the journey from Turkey into Syria through olive groves and holes in the barbed wire alongside an Egyptian fighter, who said he had made the journey to "help my Muslim brothers."
Another fighter, 26-year-old Anas from Algeria, said he was already a war veteran. He fought in his homeland's Kabylie region, east of Algiers, as well as in Kashmir. Now, he was on his way to join JAN near the town of Harem.
For Abdel Taha, who said he hails from the Islamic Movement of Uzbekistan, language has been a problem, as he takes part in the siege of the Sheikh Suleiman army base near the northern city of Aleppo.
A speaker of neither Arabic nor English, he resorted to phrases which cause mirth among his comrades, including "kill the Christians and the unbelievers".
In the heavily bombed town of Maaret al-Numan, a Libyan welcomed the AFP journalist at the front line. "Do you speak Italian?" he asked in the language he knows best, before rushing back into the fray.
In Jebel al-Akrad, four Saudi men run the online websites of Islamist groups such as JAN. They live in an abandoned apartment in the town of Salma, with a rocket-propelled grenade sitting in the living room.
Asked what they are doing in Syria, they replied: "Tourism".
Many of these fighters come to Syria with an agenda involving the establishment of an Islamist state that follows a strict interpretation of sharia law. Such a state would not necessarily be agreeable to all segments of the Syrian population, which has a diverse mix of religious sects and ethnic origins.
In January 2012, JAN leader Abu Mohammed al-Joulani, who nicknamed himself "the conqueror", said JAN had come "to restore the authority of God to his land and avenge violated honour" when he formally announced the formation of the organisation.
And while a considerable segment of the opposition may be hoping that an Islamic-oriented government is established on the ruins of the former regime, the difference between these groups and JAN is that the latter seeks to forcibly impose its vision of an Islamist state on Syria.
These differences in methodology and ideology between JAN and the rest of the Syrian opposition were the reasons researchers at the Quilliam Foundation warned that should Assad fall, JAN would attack the other opposition immediately or "occupy strategic places to negotiate their own ends".
"They see themselves as representatives of Syria's Sunni population, which is a dangerous falsehood," the Quilliam study said. "Even amongst the rebels, only a minority shares their ideology and goals, with many others, tens of thousands of activists, calling for a democratic system of government rather than an Islamist state."