[jsty]

You'd also have to consider the likelihood of one getting through your laser defences, and what the cost of protecting your country with these would be.

If you have a 99% chance of stopping a missile, but your adversary has tens or hundreds of thousands of missiles to fire at you, those aren't great odds.

Plus in a pinch, modern societies could probably come up with some fairly hideous deterrent weapons that didn't require missile delivery.

[b_tterc_p]

That’s a good point, and in fact probability of error doesn’t even need to come into play. If you can destroy 10 missiles per second with probability 1, then you have a 0% chance of stopping 11 missiles at once. Massive simplifications here but the point stands. Scale matters.