Ok to really reply to the original post instead of heading off on a tangent: Do we need a defense and weapons?
Simple answer is yes and no.
Yes we need to be able to protect ourselves but unless we can pull phasers and photon torpedoes out of our asses weapons are close to useless.
A simple mass driver and a nut is enough to take out a missile or an invading force.
"A mass driver or electromagnetic catapult is a proposed method of non-rocket spacelaunch which would use a linear motor to accelerate and catapult payloads up to high speeds." You know the things we learned about in school.
If I accelerate a pencil I can most likely punch clean through the upper stage of a missile.
No need to lasers and particle weapons just 3 or 4 mass drivers.
Now then shielding from all the bad this world can throw at us is all over earth orbit.
Buy a decomed satellite from the insurance company and place it in a strategic area. Now they have to blast that before they can blast us.
With so many 3rd stages and broken sats we could say we are trying to clean up earths orbiting junk. Place it between us and earth, maybe a second layer and we have, in effect, made shielding on the cheap for us.
Is it a sad state of affairs that we would have to do that but stop and think, all it takes is a Kim to decide he cant let us have the high ground over him, or that he thinks we are spying for whomever.
We can have cleared corridors for resupply ships protected by a mass driver.
No army needed.
No guns, bombs, lasers, particle beam weapons needed.
We take away any reason to think we are trying to rule the world.
