from Entropy
Where is the line and who draws it?
In the absence of a One World Government (which is not one of my goals), the duly constituted government in each state decides. That means that one state could decide that the situation is an armed conflict; and another state could decide it is a criminal law situation.

The bottom line is that the decision is political - not legal (despite many in the I Law "community" who would like to be the "Deciders").

The affected Violent Non-State Actor may or may not contest the State's decision. For example, AQ has not disputed that it is engaged in an armed conflict with the US.

Regards

Mike