Originally Posted by Sandy106

From what I understand the DF21 acts like a ballistic missile, because it basically is one, and the Standard Missile 3 is designed to intercpet those. From wiki:

The RIM-161 Standard Missile 3 (SM-3) is a ship based anti-ballistic missile used by the Aegis Ballistic Missile Defense System. Although primarily designed as an anti-ballistic missile, the SM-3 has also been employed in an anti-satellite capacity against a satellite at the lower end of Low Earth orbit.

So it seems like the USN could intercpet it, and if they can I dont see why its such a big deal

RIM-161 Standard Missile 3 - Wikipedia, the free encyclopedia
Aegis Ballistic Missile Defense System - Wikipedia, the free encyclopedia