'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.'