A Complex Threat Environment (CTE) is defined as an environment where both new and existing threats are composed of a number of variables, making them hard to anticipate, and thus the need for specific counter measures.
CTEs existing primarily in areas such as data privacy, where companies are vulnerable from a number of threat actors. These threat actors can emerge relatively quickly, but are usually not stackable, due to their means of operation.
Stackable Threats, when the do occur, are usually the result of a coordinated single action, appearing to take the form of multiple unconnected actions. These are often referred to as Trident actions, since each act appears independent, they are however all acting on a single item.