Do inactive defensive arms add to your defense index? I'm trying to get to lvl 2 and I want to know if activating all of my defensive weapons will get me above the 45.00 index I need.
If that still isnt enough, the most economical way (though not the best for actual defense) is to buy missile interceptor batteries, keeping them active for the index as keto says. Ammunition counts for next to nothing in the index also.