When terrorists murder at the World Trade Center, or car bombers strike in Baghdad, or hijackers plot to blow up planes over the Atlantic, or terrorist militias shoot rockets at Israeli towns, they are all pursuing the same objective -- to turn back the advance of freedom, and impose a dark vision of tyranny and terror across the world.

The enemies of liberty come from different parts of the world, and they take inspiration from different sources. Some are radicalized followers of the Sunni tradition, who swear allegiance to terrorist organizations like al Qaeda. Others are radicalized followers of the Shia tradition, who join groups like Hezbollah and take guidance from state sponsors like Syria and Iran. Still others are "homegrown" terrorists -- fanatics who live quietly in free societies they dream to destroy. Despite their differences, these groups from -- form the outlines of a single movement, a worldwide network of radicals that use terror to kill those who stand in the way of their totalitarian ideology. And the unifying feature of this movement, the link that spans sectarian divisions and local grievances, is the rigid conviction that free societies are a threat to their twisted view of Islam.

The war we fight today is more than a military conflict; it is the decisive ideological struggle of the 21st century. On one side are those who believe in the values of freedom and moderation -- the right of all people to speak, and worship, and live in liberty. And on the other side are those driven by the values of tyranny and extremism -- the right of a self-appointed few to impose their fanatical views on all the rest. As veterans, you have seen this kind of enemy before. They're successors to Fascists, to Nazis, to Communists, and other totalitarians of the 20th century. And history shows what the outcome will be: This war will be difficult; this war will be long; and this war will end in the defeat of the terrorists and totalitarians, and a victory for the cause of freedom and liberty.

We're now approaching the fifth anniversary of the day this war reached our shores. As the horror of that morning grows more distant, there is a tendency to believe that the threat is receding and this war is coming to a close. That feeling is natural and comforting -- and wrong. As we recently saw, the enemy still wants to attack us. We're in a war we didn't ask for, but it's a war we must wage, and a war we will win.