...is for its legal status (empowering the US executive to carry out certain actions it otherwise couldn't).
A number of laws were changed/reinterpreted following 9/11 with respect to what constitutes war and how it may be implemented.
Congress has authorized certain actions but there has been no declaration of war.
Something along the lines of: "In times of war...
* the battlefield is wherever the enemy is (just about anywhere you can draw a link to terrorist activity);
* the battlefield may be 'prepared' (drone strikes, assassinations, covert ops, etc).
http://en.wikipedia.org/wiki/Authorization_for_Use_of_Milita...
The United States of America is not at "War" unless there is a Declaration of War from the Congress. The Congress of the United States of America has not declared war in over 70 years.
It's not likely to happen unless this country is facing a very real, existential threat. Declaring war is like flipping a switch on our Constitutional and economic systems.
The Constitution gives the Congress the power to declare war, but the extension of that to "war doesn't exist unless Congress declares it" is reading something into the Constitution which is not expressly there, and which there is a fairly good historical argument (which every Supreme Court case to take up the issue, starting fairly early on in the Republic, also sided with) is not at all intended.
> The Congress of the United States of America has not declared war in over 70 years.
This is not true; just as Congress doesn't have to use magic words when it invokes, say, its interstate commerce power, or its taxation power, neither does it when it choses to exercise its power to declare war; acts of Congress like the 2001 "9/11 AUMF" and the 2003 "Iraq AUMF" are both examples of exercises of the power to declare war (in both cases, declarations made conditional on executive acts.)
> Declaring war is like flipping a switch on our Constitutional and economic systems.
Declaring war is not like flipping a switch on the Constitution. Nor the economic system, really, though separate radical acts in the economic arena may be premised on the existence of a state of war.
http://en.wikipedia.org/wiki/Authorization_for_Use_of_Milita...
The effect of this NATO 'trick' was that no presidents or prime ministers had to show evidence or get their parliaments to vote for the war. In effect Tony Blair's mate at NATO made the war possible with one meeting and one press conference, claiming that he had seen the evidence proving Osama bin Laden's guilt. Whatever that evidence was is something that the world didn't follow up on with NATO.