Close, but no Cigar... keep on tweeking!
"improved advanced tracking of weapons coming in across the Pacific - as they would if fired from North Korea, for example, though that nation has yet to conduct a successful test of a missile capable of reaching the continental USA"
Fortunately, a single or couple missiles from North Korea have multipe chances to be hit.
"but hit a countermeasure rather than the actual target."
Hey, this is pretty good! This is a remarkable achievement, considering opponents said this would be impossible just a decade ago. This is indicative of tweeking that is needed, rather than revamping.
It is expected that every phase will not work 100% correctly 100% of the time, which is why there are multiple technologies attacking multiple phases of a missile attack in order to conduct missile kills.
- sea based countermeasures
- air based countermeasures
- ground based countermeasures
- ascent phase kills
- mid phase kills
- descent phase kills
Multiple technologies targeting different phases in a missile defense shield, provides protection where each strategy picks up from where the other leaves off... providing citizens an effective counter measure to threats from belligerent nations.
If a counter measure is successful some of the times, lives and infrastructure would be saved, which is better than the only defense nations have today against an aggressor threatening action - full fledge pre-emptive war.
When a friendly nation has been compromised by belligerent unlawful combatants (i.e. terrorists), there is not even a countermeasure today.
The only choice is to keep on tweeking.