Intelligence officials say foreign fighters have been slipping back into Iraq in larger numbers recently and may have been behind some of the most devastating attacks this year, reviving a threat the U.S. military believed had been almost entirely eradicated.
It is impossible to verify the actual numbers of foreign insurgents entering the country. But one Middle Eastern intelligence official estimated recently that 250 came in October alone. U.S. officials say the figure is far lower, but have acknowledged an increase since August.
At the same time, Iraqi officials say there has been a surge in financial aid to al-Qaida's front group in Iraq as the U.S. military prepares to leave by the end of 2011. They said it reflects fears by Arab states over the growing influence of Iran's Shiite-led government over Iraq and its Shiite-dominated government.
On Sunday, security official Maj. Gen. Qassim al-Moussawi said Iraqi forces are searching for six foreign fighters who are among Iraq's most wanted terrorists.
The six are suspected of involvement in the Oct. 31 siege of a Christian church that left 68 people dead and drew international outrage, al-Moussawi said. They are also suspected in two summertime attacks on an Iraqi army headquarters in central Baghdad that killed a total of 73 people.
"All who committed these attacks are (non-Iraqi) Arabs," he said. "This indicates the failure of al-Qaida leaders to recruit Iraqis to carry out suicide attacks."
Al-Moussawi said five of the six suspects are hiding in two Sunni Muslim-dominated provinces bordering Syria, while one has fled to Syria.
U.S. officials are playing down the threat.
Army Col. Barry Johnson, a spokesman for U.S. forces in Iraq, said the military noticed a slight increase in foreign fighters staring in August, but would not say how many. He said the number remains far lower than when insurgents were rushing in from Arab states between 2005 and 2007.
"There were some indications of a flow of foreign fighters in," Johnson said. "And that is often associated with suicide attacks, so we were anticipating something happening."
Last year, U.S. counterterrorism officials said the number of foreigners heading to Iraq had trickled from hundreds to "tens" in what they described as a severely weakened al-Qaida in Iraq.
But a Mideast counterterrorism official said an estimated 250 foreign fighters entered Iraq in October alone. He said they came through the Syrian city of Homs, a hub for Syrian Muslim fundamentalists that is run mostly by Tunisians and Algerians. Other fighters have come from Pakistan, Saudi Arabia, Libya and Yemen.
Additionally, the official said tens of millions of foreign dollars annually are funding the Iraqi insurgency, which has received about $5 billion in aid since 2007. The money comes from al-Qaida leaders, Muslims who want the U.S. to leave, and so-called 'Arab nationalists' who are eager for Sunni Muslims to regain power in Shiite-dominated Iraq.
The official spoke on condition of anonymity because he was not authorized to brief the media.
Even at the height of the war, foreign fighters were considered a small percentage of the total insurgents in Iraq. But their presence encouraged donations from overseas, and they made up some of the most hardcore jihadists who were willing to carry out suicide bombings.
Officials see the fingerprints of foreign fighters in a spate of recent attacks:
—Four of the church bombers who were from Libya and Syria and carried fake ID cards that identified them as mutes to avoid talking in foreign accents to checkpoint guards, Iraqi Deputy Interior Minister Ahmed Abu Raghef told The Associated Press. He said $70,000 cash was seized from a western Baghdad home where their cell's leaders were operating.
—A Tunisian who was also pretending to be mute was arrested on terror charges in August in eastern Diyala province, according to an Iraqi security official who spoke on condition of anonymity because he was not authorized to talk to the media.
—A Moroccan fighter was captured and two non-Iraqi insurgents were killed in a raid last Thursday in the northern city of Mosul, said Defense Ministry spokesman Maj. Gen. Mohammed al-Askari.
—Four Jordanian fighters were killed by U.S. troops in Iraq, according to a November claim by the Islamic State of Iraq, a front group for al-Qaida.
—A Nov. 2 string of rapid-fire blasts in Shiite neighborhoods across Baghdad killed 91. Iraqi counterterrorism commander Maj. Gen. Fadhel al-Barwari said it must have been carried out with foreign financing to buy the explosives needed "to launch an attack with a big number of casualties."
U.S. officials and experts voiced doubt that the foreign aid is as high as Iraqi and Mideast authorities believe.
A senior U.S. military official who spoke on condition of anonymity to talk candidly about the sensitive issue estimated about 10 foreign fighters enter Iraq each month. Michael Knights, a Lafter Fellow at the Washington Institute for Near East Policy predicted there are only "small cells of experienced foreign fighters in ISI."
But an analysis by private global intelligence firm Stratfor concluded that foreign help in the church siege signals al-Qaida "may have found a new source for militants, and they may have more resources to carry out fresh attacks."
Associated Press Writers Rebecca Santana in Baghdad and Jamal Halaby in Amman, Jordan, contributed to this report.