Al-Qaeda forces in Syria are actively seeking recruits from Americans who have traveled there to fight or to assist opposition forces, according to U.S. officials quoted in today’s New York Times.

At least 70 American citizens have traveled to Syria, and most of them are still there, according to U.S. intelligence officials who are concerned that they could become radicalized and recruited by al-Qaeda to launch terrorist attacks when they return to the United States.

The Americans are part of a larger influx of up to 11,000 foreign fighters who have flocked to Syria. Most are Arabs who consider the war against the secular, Alawite-dominated Assad regime to be a religiously sanctioned jihad (holy war), with many coming from Saudi Arabia, Libya, and Tunisia. It is estimated that more than 1,200 European Muslims have also joined the fighting.

At least one American—Muslim convert Nicole Lynn Mansfield of Flint, Michigan—has been killed in the fighting. A North Carolina man, Basit Javed Sheikh, was charged last November with attempting to provide material support to the al-Nusra Front, one of the two al-Qaeda organizations operating inside Syria.

Eric Harroun, a U.S. Army veteran, was also arrested last year for traveling to Syria to fight alongside the al-Nusra Front. An unidentified American from Chicago, who has surfaced on Twitter and Facebook, reportedly traveled to Syria and joined the other al-Qaeda franchise there, the Islamic State of Iraq and Syria.

That organization is an outgrowth of Al-Qaeda in Iraq, which threatened to launch terrorist attacks “in the heart” of America in July 2012.

The U.S. government is also concerned about Americans radicalized in Syria because of a pattern of previous terrorist attacks launched by Islamist militants embroiled in similar conflicts. The war in Afghanistan radicalized a generation of foreign fighters who returned home to many Middle Eastern countries and became the vanguard of revolutionary terrorist organizations, including al-Qaeda.

The long-running civil war in Somali has radicalized some Somali-Americans and produced the first American suicide bomber, who died in a 2011 terrorist attack in Somalia.

One of the Tsarnaev brothers, who plotted the terrorist bombing of the Boston Marathon in April 2013, first traveled to the Russian region of Dagestan, the site of a persistent Islamist insurgency, where he may have made contact with Islamist extremists.

Clearly, the radicalization and exploitation of Americans by Islamist terrorist organizations poses a direct threat to U.S. homeland security. FBI director James Comey has stressed the bureau’s commitment to counterterrorism and yesterday stated that tracking individuals traveling between the U.S. and Syria is one of its highest counterterrorism priorities.

The FBI has scored some successes with homegrown terrorsim prevention, as seen in the recent thwarted terror plot at Wichita’s airport, but there is growing concern about the increasing threat posed by Islamist radicalization.

As the violence escalates in Syria and al-Qaeda forces infiltrate the region, the Obama Administration should present a clear and coherent strategy to effectively address the growing problem of Islamist radicalization and homegrown terrorism.