WASHINGTON, May 12 (UPI) -- FBI Director James Comey on Wednesday said that while the Islamic State is recruiting fewer Americans, messaging encryption technology is strengthening the militant group's efforts.
Comey told reporters that since August, one American a month has traveled or attempted to travel to the Middle East to join the Islamic State -- a decrease from about six to 10 a month in the previous year and a half.
"The brand has lost significant power in the U.S.," Comey said. "There's no doubt that something has happened that is lasting, in terms of the attractiveness of the nightmare which is the Islamic State to people from the United States."
Comey did not attribute the decline of American recruits to a specific cause, though the FBI intensified efforts within the past year to identify and intercept Americans who may have intent to join the Islamic State in Syria or Iraq.
"There's still a presence online, and troubled people are still turning to this and at least being interested in it," Comey said. "But they've lost their ability to attract people to their caliphate from the United States in a material way."
The use of encryption technology, including through the WhatsApp messaging service, is complicating law enforcement's efforts to protect national security, Comey said -- calling the technology a "huge feature of terrorist tradecraft."
WhatsApp, the world's most popular messaging application, in April began end-to-end encryption features -- meaning only senders and receivers of message are able to read a message's content.
"WhatsApp has over a billion customers -- overwhelmingly good people but in that billion customers are terrorists and criminals," Comey said.
Tech leaders argue stronger encryption is needed to protect their customers from threats posed by cybercriminals and hackers.