Shortly before its attack on Syria, the US declassified its “Report on the Legal and Policy Frameworks Guiding the United States’ Use of Military Force and Related National Security Operations.” As its name implies, this paper concerns itself with US military operations abroad. The word “war” is never officially used, as you may notice, because the procedure for declaring war is a rather complicated process.
According to the report, “US. forces remain in Afghanistan for the purposes of stopping the reemergence of safe havens that enable terrorists to threaten the United States or its interests.” In regard to Iraq and Syria, the picture is much the same. US armed forces are deployed “to conduct operations against ISIS with indigenous ground forces.” Such evasive wording in regard to the second group suggests that this is a reference not only to terrorists, but also to Syrian government troops. This is confirmed a bit further into the document, where it states that “US Armed Forces participating in the Defeat-ISIS campaign in Syria have taken a limited number of strikes against Syrian government and pro-Syrian government forces.” As for the Kurdish divisions, only the Iraqi Peshmerga are mentioned, although in Syria the US has also provided military assistance to the Kurdish units of the SDF.
Only a relatively small contingent of American troops have been posted to Yemen, where they are conducting operations against the local branches of al-Qaeda. In addition to taking part in combat operations, the US provides logistical assistance from Saudi Arabia against Houthi rebels.
In Somalia, the US carries out both air strikes as well as ground operations, which includes cooperation with the African Union mission in Somalia. The US has designated al-Qaeda, ISIS, and al-Shabaab as its military targets.
Libya has mostly been on the receiving end of air strikes that are supposedly coordinated with the Libyan Government of National Accord.
The seventh country mentioned in the document does not often come up in any of the various news reports about the military hostilities. This is Niger, and the official reason for the presence of the US military there is to train, assist, and advise the local government in the fight against ISIS. Moreover it states that “United States and Nigerien partner forces responded with armed force in self-defense.”