I'm struggling to find it now, but there's a saying attributed to some well known military figure (paraphrasing slightly):

There are two stages to any defence procurement project - too soon to tell, and too late to stop.

EDIT:

Found it. A Ernest Fitzgerald, and Fitzgerald's First Law: "There are only two phases of a program. The first is 'It's too early to tell.' The second: 'It's too late to stop.'