Peshawar, Pakistan —- Afghanistan has been drawing a fresh influx of jihadi fighters from Turkey, Central Asia, Chechnya and the Middle East, one more sign that al-Qaida is regrouping on what is fast becoming the most active front of the war on terrorism.

More foreigners are infiltrating Afghanistan because of a recruitment drive by al-Qaida as well as a burgeoning insurgency that has made movement easier across the border from Pakistan, U.S. officials, militants and experts say. For the past two months, Afghanistan has overtaken Iraq in deaths of U.S. and allied troops. Nine American soldiers, including two from Georgia, were killed at a remote base in Kunar province Sunday in the deadliest attack in years.

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, warned this month of an increase in foreign fighters crossing into Afghanistan from Pakistan, where a new government is trying to negotiate with militants.

Jihadist Web sites from Chechnya to Turkey to the Arab world featured recruitment ads as early as 2007 calling on the "Lions of Islam" to fight in Afghanistan, said Brian Glyn Williams, associate professor of Islamic history at the University of Massachusetts. Williams has tracked the movement of jihadis for the U.S. military's Combating Terrorism Center at West Point.

Local Afghans in the border regions are increasingly concerned about the return of the "Araban" or "Ikhwanis," as Arab fighters are known in the Pashtun language, Williams wrote in a CTC paper. He cited rumors of Arab fighters from Iraq training Afghan Pashtuns in the previously taboo tactic of suicide bombing.

Turkey also appears to have emerged as a source of recruits. Williams estimated as many as 100 Turks had made their way to Pakistan to join the fight in Afghanistan.

"The local Afghans whom I talked to claim that the Turks and other foreigners are more prone to suicidal assaults than the local Taliban," he said.

Some new recruits cross into Afghanistan's northern Balkh province or through Iran into Herat province in western Afghanistan, said Nangyal Khosti, a commander loyal to Jalaluddin Haqqani, a wanted terrorist. Those from Iran have often trained in Iraq and are hardened insurgents. The recruits, Yusuf said, head to Afghanistan's Paktika province.

In Pakistan, al-Qaida recruits are sent to Waziristan and the lawless regions of the northwest along Afghanistan's border, Yusuf said.

Afghan and Western officials say a key route for al-Qaida recruits is from Central Asia into northeastern Kunar and Nuristan provinces, where former U.S. intelligence officials suspect Osama bin Laden is hiding. Both provinces border Pakistan's Bajaur tribal area, where the Taliban holds sway and where the U.S. has targeted al-Qaida's No. 2, Ayman al-Zawahri.

While al-Qaida may be sending most of its trainees to Afghanistan and Pakistan, it is probably also creating cells with the mission of attacking Western countries, including the United States, warned Erich Marquardt, senior editor with the Combating Terrorism Center.

"I think we have to accept the fact that al-Qaida has not taken its sights off the far enemy," he said. "Al-Qaida recognizes that it is fighting in multiple theaters and is therefore likely training fighters for different areas of operation."