Mark Rowley

In London specifically, the Metropolitan Police Service has mobilised additional officers, who will carry out highly visible patrols at key locations around the capital including the transport network, we are in close liaison with the Belgium authorities and will continue to monitor the situation.

You see a terrorist group that has big ambitions for enormous and spectacular attacks, not just the types that we've seen foiled to date.

Tight organizations planning terrorist atrocities, going for complex, high-impact attacks was where we were.

They are not necessarily focused on massively complicated attacks. They are focused on the propaganda value.

Some of the acceleration of technology, whether it's communications or other spheres, can be set up in different ways, it can be set up in a way which is friendly to terrorists and helps them ... and creates challenges for law enforcement and intelligence agencies. Or it can be set up in a way which doesn't do that.

Snowden has created an environment where some technology companies are less comfortable working with law reinforcement and intelligence agencies and the bad guys are better informed, we all love the benefit of the internet and all the rest of it, but we need their support in making sure that they're doing everything possible to stop their technology being exploited by terrorists. I'm saying that needs to be front and center of their thinking and for some it is and some it isn't.