The base of operations for Rainbow is located in Hereford, England (at the time, home to the SAS), due to the United Kingdom being one of the most accessible countries in the world and having one of the world’s foremost special forces units. Most of the characters in Rainbow Six are American or British, though the NATO countries of France, Germany, Italy, Spain, Canada, and the NATO ally of Israel have at least one representative each.
Clancy describes the structure of Rainbow as having one Director, who oversees the entire operation, and one Deputy Director, who is second in command. Rainbow is portrayed as the “blacker than black” operations, and it works off its very own intelligence service which has intelligence contacts all over the world. In the book, when Rainbow is called upon for help from another country’s government to deal with a terrorist situation, usually only one of the two teams will be sent, but in some situations both will be sent. Both teams have an officer (O-4 or equivalent) as team leader and a senior NCO (E-9 or equivalent) as second in command. Not including the team leader, each team is made up of ten men. Rainbow also has a standard-issue weapons kit. Each team has two snipers.
In the video games, Rainbow is portrayed differently. John Clark is still the leader for most of the series, but is supported by a set of other key staff and advisers who vary from game to game. As of Rogue Spear, the unit has 30 operatives, including members from NATO countries and from non-NATO countries. For each mission, a maximum eight operatives can be deployed and can be split into a maximum of four teams. Weapons, uniforms, and equipment are less standardized, and are instead chosen to suit the operative and the mission.