Under the direction of Jeff Sutherland (Co-Creator of Scrum) the US Department of Defense has  begun to embrace Agile contracts for procurement.

Read a summary of the " Greater Accountability and Faster Delivery Through Modular Contracting "

Their solution is called "modular approach", where the core is incremental delivery and that the specification can be rewritten after each delivery. A typical contract shall contain at least 3 deliveries per year. Read about their procurement guidelines and order " Contracting Guidance to Support Modular Development ".

Thanks to http://agilakontrakt.se for the summary.