It's the "Concept of Operations for Natural Impact Warning Clearinghouse" dated 14 June 2002. It's not approved for general release but it isn't classified, either. It has some interesting tidbits, such as the fact that US launch detection satellites pick up an average of over 30 asteroid impacts in the upper atmosphere each year, often releasing over 10 kilotons of energy in airbursts. For perspective, the Hiroshima "Little Boy" bomb released approximately 15 kilotons. There was an approximately 1 megaton event over Greenland in 1997.

The CONOPS document primarily focuses on the need for a national clearinghouse for asteroid and comet data along the lines of NORAD's Missile Warning Center. It discusses detection systems to a degree but that isn't the primary focus of the document. Funny, it doesn't talk about the need for lunar based observatories at all. Imagine that.