Concerned about attempts by adversaries to jam global positioning satellite system signals–as occurred with only limited success during the recent Iraq conflict–the U.S. Air Force is moving ahead with plans to field a new-generation constellation of satellites, called GPS III. After a months-long logjam, the Air Force next month will begin accepting requests for proposals to develop and deploy the satellites sometime between 2010 and 2013. Former GPS III competitors Lockheed Martin and Spectrum Astro announced they are joining forces to mount a more effective offense against Boeing for the multibillion-dollar contract.