How much will new U.S. stealth bomber really cost? Nobody knows.

The Defense Department on Oct. 27 selected Northrop Grumman to build a new U.S. strategic bomber fleet. Between 80 and 100 planes are expected to be produced over the next decade. But three important questions must be answered before Congress approves significant funds for the program.

First, what will the bombers actually cost? The Air Force claims it can build 100 for no more than $564 million each. But even if that were true, the price tag does not include the development costs, estimated to exceed $20 billion.

This article was originally published in Reuters.