Title: Mission Impossible? A case study on how to manage the tension between openness and secrecy in the defense industry. Background: This thesis is built upon a unique case exhibiting open innovation within the defense industry. Practicing open innovation is a challenge for all organizations today but as a consequence of the defense industry’s high secrecy, open innovation becomes even more challenging. On one hand, they need to share internal knowledge to practice open innovation but on the other hand, sharing too much can endanger its country’s national security. The tension emerging from the need to open up an organization to practice open innovation while simultaneously maintaining secrecy results in an emergence of paradoxical tension. The literature has highlighted this tension as the paradox of openness. Purpose Research the paradox of openness within the defense industry. Methodology: An abductively qualitative single case study at the Swedish defense company Saab AB. The empirical data were collected from13 semi-structured and unstructured interviews. Findings: Selective revealing, a strong relationship and trust, internal rules and processes, and the understanding of customer capabilities are ways defense organizations can use to manage the paradox of openness in offset agreements. Keywords: Open innovation, The paradox of openness, Differentiation and integration approach, Defense industry, Saab AB, Offset, Transfer of Technology, Brazil.