How does the ocean protect America from swarms of short range drones being launched from normal looking shipping containers on trucks being controlled from thousands of miles away?
I'm not sure what that does for whoever initiates the attack. They still eventually get found out and unless they've managed to conquer the US, everyone is now bankrupt.
How far off are palm sized drones that have light weight solar panels on them that can flit about here and there and sit and wait and recharge in unobtrusive locations until they make their way to their target?