David Cameron: No point in tougher deportation if we keep letting unwanted people in

We need to do much better at stopping wars from ever starting and that means really focussing on the causes of conflicts. We've also got to think through much more carefully whether Britain should get involved in a foreign conflict, and if so, how to cope with the consequences. And then if we do intervene and send troops to fight in a foreign country, there should be a proper reconstruction force ready and waiting to deliver a stabilisation strategy as soon as the fighting stops.

The same thinking also applies to the way we handle threats here in Britain. So there's not much point having tougher laws to deport people who are a threat to Britain if at the same time we don't have a proper border police force to stop unwanted people from coming in.

There's not much point saying that the military need to be more closely involved in emergency planning if the police and fire services don't know exactly how many soldiers they can count on when the time comes. And, as Pauline Neville-Jones and Sayeeda Warsi have argued so powerfully throughout the past few years, if we're serious about stopping extremism, we've got to make sure that our anti-terrorism legislation doesn't clamp down on those freedoms we're trying to defend.

But it's not just about the people and the places which are a threat to us. It's also about thinking about the kinds of things that could go wrong. We need to plan for pandemics, energy crises and water stoppages. And in particular for what I believe is a growing cyber threat.

We know that there are hundreds of thousands of cyber-attacks and crimes against British businesses every year. I want Britain to be prepared and proactive and ready to deal with all kinds of cyber attacks. So today we're announcing plans for a new Cyber Threat and Assessment Centre to provide exactly that.

New machinery, new methods, a new way of thinking about national security. But there's also another key ingredient of a successful national security strategy. Trust. We have to take people with us and make sure that people trust the system.

Taken from a speech given by the leader of the Conservatives at Chatham House last week