Their numbers are unknown but their motives are clear.
Suicide bombers are a feature of the Israeli-Palestinian conflict
Arab volunteers have begun arriving in Iraq, vowing to help defend a Muslim nation against what they see as an unwarranted Western attack.
Iraq has proclaimed that 4,000 such volunteers are now in the country, ready to carry out suicide attacks if necessary, to repel US and British forces.
These are almost certainly not al-Qaeda operatives, although their methods and their motives are starting to look quite similar.
On Sunday, the Palestinian group Islamic Jihad announced that it had sent "the first batch of suicide bombers" to help Iraq. This is not a threat to be taken lightly, as the group has honed its methods in years of attacks on Israelis.
More volunteers will doubtless follow from other militant groups such as those in Algeria. But so far, many of those who have volunteered are ordinary Arab civilians, often family men, from Yemen, Algeria, Syria and elsewhere.
They feel so passionately about the war in Iraq they are prepared to leave behind them everything they hold dear.
Importantly, they have not come to Iraq to defend Saddam Hussein, although that is in effect what they are doing, they say they have come to protect the land of Iraq, once the centre of a mighty Islamic empire.
After weeks of hostile Arab media coverage, it should come as no surprise that some people are volunteering to fight for Iraq. When Arab viewers see daily images of bloodied bodies, crying children and bombed cities, all apparently perpetrated by non-Muslim Americans and Britons, it makes their blood boil.
They simply do not believe the Bush-Blair message that the war in Iraq is one of liberation. Too many Iraqi civilians are getting killed or wounded for that concept to take hold in the Middle East.
So, as the war drags on, Arab public opinion is starting to agree with the gist of a recent message presumed to come from Osama Bin Laden.
That a US-led war on Iraq would be an assault not so much on Saddam Hussein's regime, but on innocent Iraqi civilians.
On Monday, Egypt's President Hosni Mubarak warned that this war would create "a hundred Bin Laden's", so profound is Arab anger. Bin Laden, if he is still alive, must be telling his followers "I told you so."
He has already urged Muslims to go to Iraq's aid. Independent of his message, some are now doing exactly that.