I think you've missed a word; do you mean: explain why do presidents think that military is important.
Military is important for security, and without the military a country can't defend itself: see the attack on Pearl Harbor.
With a strong army the president has more power and cannot be threatened by other countries.
Where are the following terms
Answer:
The answer is the availability heuristic.
Explanation:
This concept explains that people heavily rely on the immediate examples that come to their minds. Because of this, some people tend to make judgements based on recently acquired news or information.
This is considered to be a "mental shortcut", although it may lead people to take rushed decisions.