The United States is increasingly participating in coalition military operations. Coalition support may be required for successful military operations and in most such operations the United States desires to share the burden. U.S. allies recognize the increased security that coalition operations can bring. Because interoperability is a key element in coalitions, RAND undertook research to help the Air Force identify potential interoperability problems that may arise in coalition air operations and to suggest nonmaterial and technology-based solutions. The research focus is on command, control, communications, intelligence, surveillance, and reconnaissance (C3ISR) systems in out-of-NATO-area operations.