Strategists who once worried that jihadists trained in Afghanistan's camps would infiltrate Iraq are today concerned that a new wave of jihadists, battle hardened in Iraq, is filtering into Afghanistan.

Last month, Newsweek reported that two Taliban regional leaders, Mohammed Daud and Hamza Sangari, traveled to Iraq and received training there from insurgents. "I'm explaining to my fighters every day the lessons I learned and my experience in Iraq," Daud told reporters. "I want to copy in Afghanistan the tactics and spirit of the glorious Iraqi resistance."

The report confirms a trend that many suspected: elements of Afghanistan's insurgency are drawing their lessons—directly and indirectly—from Iraq. In the past six months, Afghanistan has seen combat of increased scope and brutality, with more fighting now than at any point since the Taliban regime fell. The daily attacks against coalition troops and Afghan security forces by Taliban insurgents have recently been accompanied by a wave of suicide tactics-once rare in Afghanistan—which authorities attribute to foreign jihadists.

Already there have been 13 suicide attacks this year, more than double the number from last year. As in Iraq, bombers have increasingly targeted civilians, sometimes with devastating effect, such as the June suicide bombing at a Kandahar mosque that killed 19 and wounded 52. Milton Bearden, a former CIA agent specializing in Afghanistan during the Cold War, believes that recent attacks have "the fingerprints" of the Iraq insurgency.

Should we be worried about a dozen suicide bombings a year in Afghanistan when there are sometimes a dozen a week in Iraq? While the differences between the insurgencies are vast, the presence of foreign extremists in each is alarming. Unlike local resistance, for which a political settlement may be possible (as Afghanistan's government is attempting with the Taliban), foreign jihadists make insatiable demands. They deliberately aim for civilians and soft targets, allowing even a small jihadist presence to cause great devastation. Lest we forget, there were only a few scattered suicide bombings in Iraq until five months into the occupation-when foreign jihadists leveled the United Nations headquarters.

Moreover, the indigenous Taliban have adopted tactics from these foreign jihadists and from Iraqi insurgents. This year has seen a rise in high-profile kidnappings and attacks on civilians (25 aid workers have already been killed this year). The Taliban have also increased their use of roadside bombs, and have started using armor-penetrating "shaped charges," a technology pioneered in Iraq. And last week an official from Afghanistan's interior ministry claimed that the Taliban had purchased surface-to-air missiles in Iraq.

Afghanistan may be the first battlefield where insurgents have employed tactics and techniques honed in Iraq, but it won't be the last. Iraq has updated the doctrines that Afghan jihadists used to defeat the Soviet Union, along with tactics derived from conflicts in Lebanon and Palestine. The war has broadcast to a new generation how surprise and targeted brutality can stalemate a technologically and numerically superior force. The intervention in Iraq, perceived as illegitimate throughout much of the world, has united a diverse set of enemies against America.

The CIA's National Intelligence Council released a report in January which concluded that Iraq has deepened jihadist solidarity and that "The al-Qa'ida membership that was distinguished by having trained in Afghanistan will gradually dissipate, to be replaced in part by the dispersion of the experienced survivors of the conflict in Iraq." According to Bearden, today "Fallujah plays the role that Afghanistan played for Abdullah Azzam [mentor of Osama bin Laden]-not so much to create an Islamic state but to raise a legion of internationalist Islamists, a generation devoted to global jihad." Iraq's foreign jihadists, hailing from twenty-seven different countries, have now been tempered in the same forge.

We're seeing the results now in Afghanistan, and could soon see them in Egypt, Sudan, Saudi Arabia, Algeria, and Somalia, the countries from which most of the Iraqi foreign fighters hail. The idea that leaving Iraq will allow terrorists to establish bases is misleading—that is precisely what they have there now.

Carl Robichaud is a program officer at The Century Foundation. He prepares Afghanistan Watch, a digest of news, analysis, and statistics.