5 Years
In 2001, I didn't think that we would go this long without a major attack. I really thought that it would be somewhere between Israel (suffering through almost continuous terror attacks) or England (dealing with occasional IRA attacks). Instead, the strategy of engaging the enemy overseas and drawing their forces to one place to fight and die has succeeded in keeping the homeland safe. Add in the increased alertness of the domestic security services (who have been busting cells of terrorists as well as tracking and watching other interesting parties) and things are not looking too bad.
There has been a cost to pay in the war; in lives and money. But the alternative is worse. Doing nothing or returning to the policies of the 1990s won't make us safer and they sure won't defeat the enemy. The only way to end the war is to win.