On one hand
On one hand we are building super stealth aircraft and ships that might be detected and defeated by much simpler and cheaper counter measures such as drones and up-graded Exocet Missiles that sunk a lot of British ships in the Falklands War. At the same time we are trying to build counter measures to defeat ICBMs from North Korea or not often mentioned lately Russia. Its like the Cold War didn’t prove that Mutually Assured Destruction by ICBMs, bombers and subs (MAD) didn’t work for 44 years.
We feared Iraq, who had no nukes and I have heard the threat of nukes from Iran for decades.
One common ingredient in all these efforts is the humongous amount of our tax dollars poured into these projects. Many of these projects are super secret so we only hear about them if revealed as spectacular failures. Check this one: http://graphics.latimes.com/missile-defense/
Should we consider instead looking for dirty bombs in freight containers and airfreight? Would we be any more successful than keeping out drugs and illegal aliens?