If the crisis revolves around to a regional partner, combat commanders employ joint forces to deter aggression and signal u. s. commitment.

I believe the answer is: External threats

External threats refers to various threats which source come from outside united states' regions.

This type of threats usually occurs when different countries are involved in a certain type of conflict due to the failure in foreign policies.   When such threats arise, the joint forces typicall consist of several agencies and resources which taken nationwide.

answer; motor learning;