Asymmetric warfare has been a game changer. It's all about "mass" on target. It's more effective (and possible) to build and fire a 100 rockets that cost a 1000 dollars to make. Than fire a single 100.000 dollar one.
Back in 2002 the US navy found out that just overwhelming defences with a large amount of projectiles could sink an aircraft carrier. In this case a in a wargame which led to some controversy after they covered it up.