The FBI warned Congress on Wednesday that Syria is quickly becoming a haven for terrorists looking to do harm to the U.S. and its allies.
A recent flood of militants into the country poses a "serious challenge" for counterterrorism officials, who are increasingly concerned that Westerners in the country could be trained to plan and carry out attacks around the world, FBI Director James Comey said.
"It's one of the things that I meant by the metastasizing threat," said Comey, appearing before a House Appropriations subcommittee. "We're very worried about people who [are] there, who travel out to the E.U. and then can come to the U.S. without a visa, or our citizens who travel back and forth directly."
Comey's comment follows a New York Times report that al-Qaida operatives are traveling from Pakistan into Syria as part of a coordinated plot to carry out future terrorist strikes against the U.S. and Europe.
Al-Qaida's senior Pakistani leadership is hoping to use chunks of largely ungoverned territory within Syria to recruit and train Westerners—beyond the reach of drone attacks, which U.S. officials are hesitant to use in the war-torn country.
Comey said the poorly or lightly governed spaces in Syria and other countries have allowed the growth of a global terror threat "that is weaker in the core, but disparate and virulent in a lot of different places."
Approximately 1,200 Americans and European Muslims have traveled to Syria to fight in the country's civil war, which started in 2011, The Times notes.
The FBI director said earlier this year that U.S. officials are using a multitude of ways to track Americans in Syria, including electronic spying, travel records, information from sources inside Syria, and data provided by the European Union.
Subcommittee Chairman Frank Wolf, R-Va., introduced legislation earlier this month that would allow the president to restrict U.S. travel and material support to countries that have terrorist organizations engaged in an armed conflict within the country—including Syria.
Comey says he is generally supportive of the legislation.