FBI Director James Comey says the flow of Western fighters into Syria — and the prospect they'll return home radicalized — represents one of his biggest day-to-day concerns.

In an interview with reporters in Washington, Comey says the situation in Syria is "getting worse," with a couple of dozen more Americans heading overseas in recent months, beyond the 60 or 70 individuals who've already ventured to the Middle East to take part in a civil war inflected with al-Qaida influences. He says the FBI has evidence that Americans in Syria are presently recruiting other U.S. citizens or green-card holders to join the fight, but refuses to offer much detail about that.

"All of us with a memory of the '80s and '90s saw the line drawn from Afghanistan to Sept. 11," Comey says. "We see Syria as that, but an order of magnitude worse in a couple of respects," because of the greater numbers of people venturing there and the ease with which they can travel on Western passports, he adds.

"There's going to be a diaspora out of Syria at some point, and we are determined not to let lines be drawn from Syria today to a future 9/11," Comey says.

Foreign counterparts are equally committed. The deputy U.S. attorney general is heading to Brussels next week to meet with European ministers about the threat.

Aside from terrorism and the homegrown extremism that helped spur last year's Boston Marathon bombing, Comey says he spends "a ton" of time on how to counter and investigate cyberattacks, both national-security-related intrusions and large, sophisticated criminal intrusions through botnets. Comey says the FBI is working to train state and local law enforcement to pursue cases with smaller financial losses.

He says the bureau needs to "redouble our efforts" to reach out to people in the Muslim community after reports and lawsuits filed by Muslim American men arguing that they had been pressured into acting as informants for the FBI and placed on watch lists if they had refused.

"That's not true, and I'm very proud of the way we interact with all communities in this diverse country," Comey says.

And on a few hot-button issues, Comey says:

--The FBI has not yet been asked to take any steps to investigate criminal referrals by the CIA and the Senate Select Committee on Intelligence over cross-claims about access to unauthorized materials that cover the CIA's alleged torture of terrorism suspects. "So far, we're not involved," he says.

--As for the troubled military commission trials for 9/11 plotters that have foundered over detainee mistreatment and sharing of classified information, Comey says questions about logistics and efficiency are valid, but "I don't think I want to answer."

--The case against former National Security Agency contractor Edward Snowden for leaking documents about mass surveillance is still open. "He's still charged and a fugitive," Comey says. "If you know us at the FBI, we never give up." Other law enforcement sources tell NPR no active plea negotiations with Snowden and his American legal team are underway.

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