According to this Huffington Post article, the groups we are war with are classified and the reasoning is as follows:
“Because elements that might be considered ‘associated forces’ can build credibility by being listed as such by the United States, we have classified the list,” said the spokesman, Lt. Col. Jim Gregory. “We cannot afford to inflate these organizations that rely on violent extremist ideology to strengthen their ranks.”
While on the surface, such a claim may seem reasonable, one has to consider this; when the democratic government of a society is blowing people up in foreign countries, regardless of anything, the citizens behind such a democratic government ought to know about it.
Moreover, this whole issue brings up what many civil libertarians, progressives and others feared; the bastardization and vagueness behind “associated forces” that allows for the U.S. government to go after Somalian terrorist in Somalia, which seems far beyond the purview of the Authorization for Use of Military Force (AUMF), itself a flawed piece of reactionary legislation.
Government secrecy is a dangerous game to play, especially when they are interpreting vague laws to meet their agendas.