The owner, a former Mujahidin fighter, openly boasts of his exploits and those of his comrades still fighting the war against US forces. Like many veterans he is eager to recount his adventures in the hope of persuading others to join the cause.

A Syrian mother said that her son, a taxi driver, had succumbed to the call to arms last month and set off with a friend on the trail to Iraq, never to be heard of again.

Like thousands of other young men, drawn from across the Arab world and from Muslim communities as far away as Spain, France and even Sheffield, his final point of departure was Syria.

“It’s an individual decision. Once you’ve decided, you go to a mosque to make the initial contact. Then you are sent to a private home and from there for a week’s intensive training inside Syria,” she said. According to former fighters who spoke to The Times in Damascus, volunteers are given a crash course in using Kalashnikov rifles, firing rocket-propelled grenades and the use of remote detonators. The training takes place at secret camps in the Syrian desert, near the Iraqi border. Some attacks are even planned in advance in Damascus and Aleppo. Once the team is ready, a guide leads them across the rugged border into Iraq where they are taken to a safe house.

Most are filtered down the Euphrates river valley to join the insurgency’s combat cells, others crossing in the north head for the town of Tal Afar and the northern capital, Mosul.

Once dismissed as a small and insignificant part of the insurgency in Iraq, the US military now concedes that the threat posed by foreign fighters is one of the most dangerous they face.

If the might of the US military was humbled in South East Asia thanks in large part to the Ho Chi Min Trail, the jungle supply route that fed insurgents in South Vietnam, then American forces in Iraq today face no less a challenge from the fanatics who cross into Iraq from Syria.

Over the past few weeks US Marines have carried out a series of offensives in the western Iraqi province of Anbar to try to smash the Euphrates supply line, yet most of the towns along the river valley remain in rebel hands. The main border town of al-Qaim is even nicknamed the “jihad superbowl” by US forces.

“The way ahead is not going to be easy,” President Bush conceded yesterday, after meeting Ibrahim al- Jaafari, the visiting Iraqi Prime Minister, at the White House. “The enemy’s goal is to drive us out of Iraq before the Iraqis have established a secure, democratic government. They will not succeed.” General John Abizaid, the commander of the US Central Command, which is responsible for Iraq, told Congress on Thursday that he believed that more foreign fighters were entering the country now than six months ago.

Exact figures are hard to come by, but it is believed that several thousand fighters are in the country. Some are remnants of the thousands who poured in during the US-led invasion of Iraq. According to Lieutenant-General JohnVines, the commander of coalition forces in Iraq, 150 foreign volunteers now cross into the country from Syria every month.

This week US forces raiding a hideout near the Syrian border found passports from Sudan, Saudi Arabia, Libya, Algeria and Tunisia. There was even a return airline ticket from Tripoli to Damascus.

They represent only a fraction of the estimated 20,000-strong insurgent force and it is the most potent weapon in the rebel arsenal. Led by Abu Musab al-Zarqawi, a Jordanian fugitive who heads al-Qaeda in Iraq, most of the foreigners are used as volunteers for suicide car bomb attacks. Since the handover of sovereignty in Iraq a year ago, there have been 479 car bombers killing 2,174 people and wounding 5,520. In the latest incident, 6 US soldiers were killed and 13 Marines were wounded yesterday in a suicide attack in Fallujah, a town that was supposed to be under complete US military control.

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