And that's the point, they are testing a missile against targets at much higher orbits. 14A042 is pretty enormous for a mobile missile.

They are aiming to take out US missile target discrimination system, the weakest link in the new US missile defence system.

https://en.m.wikipedia.org/wiki/Space_Tracking_and_Surveilla...

Without target discrimination, the missile defence will be completely exhausted by decoys.