The two car bomb attacks in Iraq last Saturday, which killed at least 18 people, have fuelled more speculation about the shadowy role being played by foreign extremists who may have infiltrated Iraq.
A US military spokesman in Baghdad has confirmed that 307 suspected "foreign fighters" are currently in detention.
They include 140 Syrians, 70 Iranians, as well as foreign nationals from other parts of the Arab world - Saudi Arabia, Yemen, the West Bank, and even as far afield as Chad.
Suicide bombers attacked two police stations on Saturday
"We're not seeing a huge influx, but it is a trickle," said the spokesman.
The widespread suspicion is that foreign militants, possibly with links to al-Qaeda, may be responsible for the suicide bomb attacks in Iraq over the past few months.
These well-planned, high-profile operations, such as the bombing of the UN headquarters, the International Committee of the Red Cross in Baghdad and the Italian police base in Nasiriya, are not thought to have been carried out by Iraqis.
No obvious link
On each occasion, there is said not to have been any obvious link with "former regime loyalists" - Iraqis who have been waging an insurgency against the US-led occupation and mounting hundreds of attacks on coalition forces and other targets.
Furthermore, the suicide bombings are not regarded as characteristic of Iraqis.
"Former regime loyalists and Baathists are not anxious to die for their cause," the US spokesman said.
"What they want, is to have their privileged way of life back. On the other hand, the foreign fighters come into Iraq as young, unemployed Jihadists convinced that the purpose of their existence is to die for their cause".
What US military commanders need most, is more intelligence.
That is why the rapid recruitment of more Iraqi police and other members of the new security services is now such a priority.
"Let's be frank. We knew nothing about this country when we came in here," said one coalition source in Baghdad.
"This was a country that had been ruled by demagogues for years."
When questioned about the connection between foreign fighters and Iraqi insurgents, coalition officials are vague and uncertain.
Earlier this month, the commander of US forces in Iraq, Lt General Ricardo Sanchez, announced that at one point, the coalition had had up to 20 suspected al-Qaeda members in custody.
Iraqi infrastructure has also been a target
He admitted however, that after interrogation, the link to al-Qaeda had not been proven.
So while there may be an unholy alliance of convenience between the various groups opposed to Iraq's occupation, the coalition has yet to find the evidence.
In spite of the devastation caused by the succession of suicide bombings, Saddam loyalists remain the coalition's primary enemy.
It's believed that these dissident Iraqis are responsible for the overwhelming number of attacks on American forces and those working with the coalition - in particular, the Iraqi police.
Iraqis await peace
In the meantime, the majority of the Iraqi population is sitting on the sidelines, anxiously watching and waiting to see how the coalition deals with a security nightmare.
It shows little sign of improvement.
The United States insists it will not abandon Iraq, but the coalition forces here appear now to be confronting both the global war on terror as well as the remnants of Saddam Hussein's regime.