Glenn Greenwald makes clear that endless war is the official policy by US politicians. The war on terror is planned to continue indefinitely without geographic boundaries, why? Because weapons manufactures make immense profit off international conflicts and, as Greenwald says:
A state of endless war justifies ever-increasing state power and secrecy and a further erosion of rights
And why is there always a new enemy to fight? Because our actions in the world create the conflicts and radicals that are used to justify more aggression. Greenwald states:
The great contradiction of American foreign policy is that the very actions endlessly rationalized as necessary for combating Terrorism — invading, occupying and bombing other countries, limitless interference in the Muslim world, unconditional support for Israeli aggression, vast civil liberties abridgments such as torture, renditions, due-process-free imprisonments — are the very actions that fuel the anti-American hatred which, as the U.S. Government itself has long recognized, is what causes, fuels and exacerbates the Terrorism we’re ostensibly attempting to address.
It’s really quite simple: if we continue to bring violence to that part of the world, then that part of the world — and those who sympathize with it — will continue to want to bring violence to the U.S.
And how else are these aggressive acts of war justified and sold to the American public? Well, “humanitarianism” is always a justification for aggression, but is always a pretense not a purpose. See this panel discussion on topic of humanitarian intervention: