Here’s how the U.S. actually makes decisions on when to go to war:
First. Decisions are made based – not upon defense – but upon gaining economic and geostrategic advantage.
For example, America has a policy of using the military to contain China’s growing economic influence – and of considering economic rivalry to be a basis for war.
And many recent battles are really pipeline wars.
Second. A massive propaganda and demonization campaign is launched in order to drum up support for the war.
There doesn’t need to be a shred of truth underlying the campaign. The p.r. flacks just have to come up with catchy slogans, and the mainstream megaphone is guaranteed to trumpet it into every living room in America.
Third. We pull the trigger, reap whatever economic/geo-strategic benefits are to be gained, and ignore the rest.
If this sounds over-the-top, remember that reducing terrorism and increasing our national security is pretty straightforward. It’s not rocket science.
The fact that we’re doing the exact opposite shows that there are other motives in play.
Postscript: I’m not picking on the U.S. I would imagine that all late-stage empires make decisions of war and peace the same way.