With a good ol' conventional start, I'm 100 years in, and still haven't developed a system (short of massive swarming) to deal with the invaders. Specifically of problem is intercepting their plasma torpedoes. I seem to be able to intercept them, but when I do, with 4:1 AMM that have a 90-odd-percent hit rate, a number of them fail to detonate the warhead.
What's the solution? Will a larger warhead on my AMM increase the chance of detonating the target's warhead? Is this some hidden result of the target missile having ECM?