When I was growing up it was 'Communists'. Now it's 'Terrorists'. So you always have to have somebody to fight and be afraid of so the war machine can build more bombs guns and bullets and everything.

With those attacks the terrorists and their supporters declared war on the United States. And war is what they got.

The terrorists and their supporters declared war on the United States - and war is what they got.

Four years ago I promised to end the war in Iraq. We did. I promised to refocus on the terrorists who actually attacked us on 9/11. We have. We've blunted the Taliban's momentum in Afghanistan and in 2014 our longest war will be over. A new tower rises above the New York skyline al Qaeda is on the path to defeat and Osama bin Laden is dead.

To a considerable extent we are faced by a technology arms race with terrorists. The communications revolution has made it easier for terrorist groups to reach out to vulnerable individuals with their violent extremist ideology and propaganda. It has also facilitated fundraising recruitment and training.

Countries across the world are taking action now to help them track paedophiles and terrorists who abuse new technology to plot their horrific crimes.

If the terrorists have the sympathy of people it's much harder to find them. So we need people on our side and that leads us to be responsible leaders of the world show some concern with the problems.

When terrorists attacked the symbols of our national unity and strength they failed to realize that they were just symbols of our strength. The real strength of our nation comes from our people - not our buildings.

Terrorists have failed to trigger mass conflict between Muslims and non-Muslims in Europe. We should draw strength from that fact.

And the truth is those who are terrorists only have to succeed once and those of us who are trying to build an inclusive society have to succeed every time.

There are many who lust for the simple answers of doctrine or decree. They are on the left and right. They are not confined to a single part of the society. They are terrorists of the mind.

In a sad twist of fate the bill to reauthorize the Patriot Act was debated on the floor of the House of Representatives the same day that terrorists struck again.

I'm proud of my invention but I'm sad that it is used by terrorists.

It's a bit odd that nobody seems to be using the correct technical term to describe organized Islamic terrorists. They are not a faction of a religion or a social movement. They are a cult. A suicide cult.

I say to the Taliban: surrender the terrorists or surrender power. It's your choice.

You cannot make peace with terrorists. The normal dividing lines between war and peace do not apply.

If terror groups are to be defeated it is national governments that will have to do so. In nations like India governments will have to call on the patriotism of citizens to fight the terrorists. In a nation like Pakistan the government will have to be persuaded to deal with those in their midst who are complicit.