Rich Abott, Defense Daily, reported statements made at Wednesdays Space and Missile Defense Symposium.

The director of the Missile Defense Agency (MDA) Air Force Lt. Gen. Samuel Greaves said the agency is developing options to pursue space-based interceptor capability.

Griffin believes that detailed work can find affordable approaches. Many old designs had unrealistically high, uninformed cost estimates. Griffin said he has seen up to 50 cost estimates but none were recent so we do not know costs at this point.

Griffin believes space-based interceptors to go after ballistic missiles in the boost phase is a relatively easy technological challenge.

The U.S. is developing a range of hypersonic attack capabilities from near-term deployment options to longer-term Air Force and DARPA air-breathing efforts like the Hypersonic Conventional Strike Weapon program (called Hacksaw) and the Air-Launched Rapid Response Weapon (called Arrow).

Griffin does not know which hypersonic attack systems will win out. He said that is why we have DARPA, to explore advanced technological options.