Terrorists go after civilians, wear no thing as a uniform and they try to blend in with the population in hopes of not getting caught. There are no standards that can dictate how they will act, and or what their goal is. They murder women, children, and anyone they please.
However, Conventional warfare, is a set of battles army vs. army. Take World War II as an example. Germany and its allies got their militaries together and fought against their allies. It is a military on military conflict. Both sides wear the uniform and only fight against those who wear the uniform in hopes of defeating the other force that withstands military might.
There are many ways for this to happen. The president can make bills. This isn't always effective as they can be rejected by congress. The president can also wage war. He has to be careful when doing this as it could backfire on him.
