Estimates that up to 11,000 foreign fighters from 74 countries have gone to fight in Syria have created mounting concern for policymakers that the war there is creating a battle-hardened jihadist cadre prepared to target the West.

In December, the Britain-based International Centre for the Study of Radicalisation reported that since late 2011 as many as 11,000 people from at least 74 countries had traveled to Syria to fight alongside rebel forces.

The ICSR said the high figure of 11,000 was double the number it had estimated in April.

The research group estimated in December that as many as 1,937 foreign fighters from Western Europe (a figure more than triple its April estimate) had traveled to Syria.

The Los Angeles Times last month quoted U.S. intelligence officials as saying that at least 50 Americans had joined the various radical groups fighting to overthrow Syrian President Bashar Assad.

Officials added that the war in Syria has become one of the biggest magnets for Islamic extremists since the 1980s, when jihadists flocked to Afghanistan to fight the Soviet Army which occupied the country.

In recent congressional testimony, National Intelligence Director James Clapper pointed to  a small group of al-Qaida operatives who have fought in Pakistan and Afghanistan and seek to attack the United States.

“Not only are fighters being drawn to Syria, but so are technologies and techniques that pose particular problems to our defenses,” Clapper told the Senate Intelligence Committee Feb. 4.

CIA Director John Brennan said that al-Qaida is training fighters at camps in Syria and neighboring Iraq and expressed concern “about the use of Syrian territory by the al-Qaida organization to recruit individuals…to use Syria as a launching pad” for attacking the West.

Homeland Security Secretary Jeh Johnson said said U.S. intelligence and law-enforcement officials know that persons from Europe and North America are heading to Syria. He said they “will encounter radical, extremist influences” and may return to their home nations intending to do harm.

For the United States, “Syria has become a matter of homeland security,” Johnson said. 

FBI Director James Comey has said that counter-terrorism officials are attempting to track American veterans of the war in Syria who have returned to the United States.

One who did not make it back was Nicole Lynn Mansfield, 33, of Flint, Mich., a convert to Islam who died in an ambush last May while with rebels in northern Syria.

Last  spring, U.S. Army veteran Eric Harroun was arrested after returning to the United States from Syria. He reportedly admitted fighting alongside the al-Qaida linked Al-Nusra Front. But Justice Department prosecutors allowed him to plead guilty to a less serious charge in September and he was sentenced to time served.

In an effort to deter Americans from joining jihadists in Syria, Virginia Rep. Frank Wolf has introduced legislation that would prohibit travel to that country without a license and bar Americans from providing material support to pro- or anti-government forces operating in Syria. Violators could be sentenced to up to 20 years imprisonment.

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