Lt. Gen. Samuel Greaves told the McAleese/Credit Suisse conference that satellites would use mature technology and could perform other surveillance missions to help justify their cost.
ICBMs have followed smooth ballistic path trajectories which are easy to track.
Increasing use of countermeasures on conventional ballistic missiles — decoys or less brightly-burning propellants — will mean missiles will need continuous monitoring while in flight. Hypersonic warheads and hypersonic missiles will be able to change direction which will require constant in-flight monitoring.
A new space-based sensor system cannot be built with MDA’s current budget. US Air Force funding would be needed.