Summarizing a new Government Accountability Office study, the Washington Post reports that “the cost of building and operating the controversial U.S. ballistic missile sites in Europe could substantially exceed the original estimate of more than $4 billion.”

It turns out that the Pentagon’s budget estimates left out the costs of numerous components of the proposed facilities, such as the costs of housing, utilities, and security. Whoops!

Revised estimates show that the costs of sites in Poland and the Czech Republic, for example, will be about $1.2 billion, or 43 percent more than originally claimed.

These facilities may or may not be a good idea from a policy perspective, but it would be nice if officials provided realistic cost estimates before projects are moved so far down the road that they become difficult to cancel. Unfortunately, the low-balling of cost estimates is a common pattern in federal defense procurement.