Top police officials from New York, London and elsewhere met Thursday to share strategies for combating the homegrown terror threat posed by self-radicalized people who are difficult to thwart because they keep to themselves.

“If the conspiracy to commit a terrorist act is a conspiracy of one, and the planning for that is unsophisticated, doesn’t require a lot pre-operational surveillance and is only happening in the mind of the offender, from an intelligence standpoint, from a prevention standpoint, that’s very hard to detect,” John Miller, head of counterterrorism for the New York Police Department, said following the conference at NYPD headquarters in Manhattan.

Miller’s remarks came at a news conference that included New York Police Commissioner William Bratton, Los Angeles Police Chief Charlie Beck and Sir Bernard Hogan-Howe, commissioner of London’s Metropolitan Police Service.

The officials said that they share a concern over the influence of a sophisticated social media outreach campaign by al-Qaida, the Islamic State group and others geared in part toward inciting shootings and other violence by troubled individuals — sometimes referred to as “lone wolves” — without any of the direct indoctrination seen in more ambitious plots. They cited the recent fatal shooting of a Canadian soldier in Ottawa and the attack on NYPD patrolmen by a hatchet-wielding man as examples of the phenomenon.

“We’ve discussed how we have a common problem, a common enemy, and how we need to act against that,” Hogan-Howe said. “Things are changing in different parts of the Middle East, and these are things that actually materialize on the streets of our countries. We have to work together to deal with that.”

Bratton said the NYPD is investing more time and resources in monitoring Muslim extremist-influenced websites and social media and is looking for ways to identify people who may be falling under their anti-Western spell. He and others also said they see better ways for police to build trust in Muslim communities to encourage people there to report changes in behavior in loved ones or friends that could be warning signs of a threat.

“Although they’re said to be lone wolves, they usually know someone who cares for them or they’re in contact with, and those people will notice that type of change of behavior,” Hogan-Howe said.

The Metropolitan Police’s website encourages citizens to report Web content that’s intended “to promote, glorify or help carry out acts of terrorism and violent extremism.” It says it has officers assigned to investigate sites and to seek ways to remove the material.

(AP)