Question

National security policy is a balancing act between

Answer 1

The question is asking is to state the two terms that the national security policy that is balancely acted between and base on my research, I would say that the answer would be Military force and Diplomacy. I hope you are satisfied with my answer and feel free to ask for more 

Answer 2

I believe the answer is: Military force and Diplomacy

Diplomacy is the act of building good relationship with another nations, while military force determine the strength of your military power compared to other nation's.
In national security, diplomacy is a measurement to prevent conflict before it happens while military force is an emergency tools in case worst case scenario happened.