When they attack us in an Act of War, then they have declared war on us. Until then, I'd say we should stick to the terrorist groups who have already attacked us.
Slow down, hoss. You said, "I believe the enemy is "terrorist groups of global reach". Now, its only if they attack us. So its pretty much whoever King George tells the pesants it is, right?
Prior wars have benefitted from a clear understanding of who the "belligerents" are and who are the "neutrals". If the Taliban had made some pretext that they were attempting to turn over OBL, then they might be a "neutral". Failure to do so should have provoked a second declaration of war against the government of Afghanistan for enabling our enemies. As things stand without formal declarations of war, there is no way for a "neutral" nation to understand unambiguously what they must or must not do.
I suggest that a reading of the beginning of the Declaration of Independence is in order here.
"...a decent respect to the opinions of mankind requires that they should declare the causes which impel them ..."