Hundreds, perhaps even thousands of volunteers have crossed into Iraq since the war there started.
There are reports that they are still fighting American forces in areas abandoned by Iraqi troops.
Many of those young men came from Syria and included Palestinian refugees.
The influx of Arab volunteers is thought to have stopped two days ago.
Arab volunteers from all over the region crossed into Iraq to fight
At the offices of the radical Palestinian group Hamas at Yarmouk Palestinian refugee camp in Damascus the walls are covered with Palestinian flags and pictures of Palestinian martyrs, but the cause today is not Palestine - it is Iraq.
Talal Hussein, the local Hamas representative, explained why:
"Iraqis are losing the war because they don't have the real Islamic faith. If the situation requires it, the jihad against the Americans will continue," he said.
"If the Iraqis asked us to stop fighting, we wouldn't because their request would be a result of American pressure. No-one would ask a fighter to stop a jihad against an occupier," he added.
Mr Hussein was in Baghdad himself for three days at the beginning of April, but he is reluctant to say what the purpose of his trip was.
He also says Hamas is not officially sending volunteers to Iraq, but it is not stopping anyone from going either.
I would give all my seven children if I had to for the cause to go fight the jihad, to be martyrs
Halate Hishul, mother of dead volunteer fighter
"Thirty young men from this camp have already died in the fighting in Iraq. Dozens more are still in Iraq. No-one has heard from them for a few days already," he said.
At the camp there are young men who came back after fighting in Iraq for about 10 days.
They say they went by bus to Baghdad and were put up at the Palestine Hotel, the same hotel where foreign journalists were staying.
They say whilst there they were interviewed by members of the Iraqi Republican Guard, and one of them was sent back immediately after he told the Iraqis he had a family and children.
Some of their friends who have also returned were fighting in Basra and Mosul.
Iraqi exile's fear
Throughout the camp the "jihad" or holy war against the Americans is on everybody's lips.
Halate Hishul's eldest son Hassam died 10 days ago on the road to Baghdad, but she does not want anyone to offer any condolences. She wants to be congratulated for the new "shaheed", or martyr, in the family.
"I would give all my seven children if I had to for the cause to go fight the jihad, to be martyrs. He was our pride, he was a fine young man," she said.
This could be the West Bank or Gaza, but it is not - it is Damascus.
Iraqis in Syria say these fighters remind them not of Palestinian suicide bombers, but of the Arab volunteers who fought with the Taleban in Afghanistan. These volunteers, known as Arab Afghans, were hated by the local population.
Iraqi exiles in Syria now say they are worried about Arab volunteers in Iraq, worried they might fight on even after the collapse of the Iraqi leadership.
Iraqis here fear this does not bode well for the stability of their country.