`Cause neither has the technology to do anything, yet.
Why put a huge amount of BMD equipment when you could just drop a penetrating GBU-28 on their "Launch Pad?" AEGIS DDGs and CGs are patrolling off Japan, and the new X-band radar installed south of Alaska gives us plenty of protection there.
Remember, the NK's couldn't even get thier Tapodong 30 seconds into flight. Their "nuclear test" was a failure (mostly; it did explode, but not with any truly damaging force, about 1/2 kiloton or less). Iran, to our knowledge, does not have nukes, either.
__________________
|