How Long Will the War on Terror Last?

On October 21,2001, shortly after the U.S. invaded Afghanistan, George Stephanopoulos in an interview with the Chairman of the Joint Chiefs of Staff, General Richard Meyers, asked:

 STEPHANOPOULOS: But how will we know when this war is won? Vice President Cheney says it might not end in our lifetime.

 MYERS: I think that may be correct. I think this is going to be a long, hard-fought conflict, and it will be global in scale, and it won't be, as I mentioned earlier, it won't be just military. It's going to be all the instruments of our national power with our friends and allies. And the fact that it could last several years or many years or maybe our lifetimes would not surprise me.