The US Central Intelligence Agency director John Brennan claims social media and other technologies have made it increasingly difficult to combat militants who are using such modern resources to share information and conduct operations.

Speaking at the Council on Foreign Relations, Brennan says such communications add to the difficulty of dealing with diffuse threats and attacks across the world from groups such as ISIS, as well as others.

“The overall threat of terrorism is greatly amplified by today's interconnected world, where an incident in one corner of the globe can instantly spark a reaction thousands of miles away; and where a lone extremist can go online and learn how to carry out an attack without ever leaving home,” Brennan said.

"These attacks underscore a disturbing trend that we have been monitoring for some time: The emergence of a terrorist threat that is increasingly decentralised, difficult to track, and difficult to thwart,” he says.

“While US agencies have boosted efforts against cyber-based threats, those bent on committing acts of terrorism have also improved their use of technologies.

Brennan said a variety of strategies, including monitoring social media, were needed to help identify threats. “We need to have a better sense of what's happening in the streets,” he says.

“And that's why looking at social media and other things you can maybe have a better sense of the barometric conditions in a country that are going to be more conducive to the forming of a storm.