Neither the Taliban militia nor the Al Qaeda terrorist network is considered a sovereign nation and therefore a declaration of war is not appropriate in this war.
Likewise, the United States never considered the Confederate States of America to be a sovereign nation and war was never declared by Congress during the Civil War.
Prior to the Barbary War, Congress debated whether or not to declare war on the Barbary States. Congress decided that the Barbary States were no more than a collection of pirates and to declare war would dignify them with the status of sovereign states. Therefore, Congress refused to declare war and instead passed an Authorization to Use Force.
In the same Barbary War, President Thomas Jefferson stated that a declaration of war was unnecessary, whether the Barbary States were sovereign states or not, because the Barbary States had already caused a state of war to exist by attacking the United States and therefore a state of war already existed. In other words, Thomas Jefferson recognized that a Declaration of War was a diplomatic courtesy between sovereign states before the bullets started flying.
#1050 for consideration.