New York (CNN)The New York Police Department and other law enforcement agencies around the nation are increasing their surveillance of ISIS supporters in the U.S., in part to aid the FBI which is struggling to keep up with a surge in the number of possible terror suspects, according to law enforcement officials.
FBI struggling with surge in homegrown terror cases
The change is part of the fallout from the terrorist attack in Garland, Texas earlier this month. The FBI says two ISIS supporters attempted a gun attack on a Prophet Mohammad cartoon contest but were killed by police. One of the attackers, Elton Simpson, was already under investigation by the FBI but managed to elude surveillance to attempt the foiled attack.
FBI Director James Comey told a group of police officials around the country in a secure conference call this month that the FBI needs help to keep tabs on hundreds of suspects.
As a result, some police agencies are adding surveillance teams to help the FBI monitor suspects. Teams of NYPD officers trained in surveillance are now helping the FBI's surveillance teams to better keep track of suspects, law enforcement officials say.
NYPD Commissioner William Bratton has said he wants to add 450 officers to the force's counterterrorism unit, partly to counter the increasing domestic threat posed by ISIS sympathizers.
The same is happening with other police departments around the country. The Los Angeles Police Department's counterterrorism unit is also beefing up its surveillance squads at the request of the FBI, law enforcement officials say.
Comey said at an unrelated news conference Wednesday that he has less confidence now that the FBI can keep up with the task.
"It's an extraordinarily difficult challenge task to find -- that's the first challenge -- and then assess those who may be on a journey from talking to doing and to find and assess in an environment where increasingly, as the attorney general said, their communications are unavailable to us even with court orders," Comey said.
"They're on encrypted platforms, so it is an incredibly difficult task that we are enlisting all of our state, local and federal partners in and we're working on it every single day, but I can't stand here with any high confidence when I confront the world that is increasingly dark to me and tell you that I've got it all covered," he said. "We are working very, very hard on it but it is an enormous task."
On Saturday, an FBI spokesman said the bureau doesn't have a shortage of resources and the Garland attack wasn't the result of lack of surveillance personnel. If agents had any indication that Simpson was moving toward an attack, they would have done everything to stop it, the spokesman said.
The appeal for local help isn't intended to seek more surveillance, but more broadly to encourage local law enforcement to increase vigilance given the heightened threat, the FBI said.
The Garland attack prompted a reassessment for FBI officials. Simpson's social media and other communications with known ISIS recruiters drew the FBI's interest earlier this year.
FBI agents in Phoenix began regular surveillance of Simpson, though it was not round-the-clock monitoring, according to a U.S. official. The agents watching Simpson noticed he disappeared for a few days.
Investigators looked into his communications and found social media postings making reference to the Garland cartoon contest. That discovery is what prompted the FBI to send a bulletin to the joint terrorism task force that was monitoring the Garland event. The bulletin arrived about three hours before the attack.
Comey told reporters this month the FBI had no idea Simpson planned to attack the event or even that he had traveled from his home in Phoenix to Texas.