Rainbow Six
Tom Clancy's Rainbow Six is a media franchise
Media franchise
A media franchise is an intellectual property involving the characters, setting and trademarks of an original work of media , such as a film, a work of literature, a television program or a video game. Generally, a whole series is made in a particular medium, along with merchandising and endorsements...

 created by American author Tom Clancy
Tom Clancy
Thomas Leo "Tom" Clancy, Jr. is an American author, best known for his technically detailed espionage, military science, and techno thriller storylines set during and in the aftermath of the Cold War, along with video games on which he did not work, but which bear his name for licensing and...

 about a fictional international
International relations
International relations is the study of relationships between countries, including the roles of states, inter-governmental organizations , international nongovernmental organizations , non-governmental organizations and multinational corporations...

 counter-terrorist unit called "Rainbow." The franchise began with Clancy's novel Rainbow Six
Rainbow Six (novel)
Rainbow Six is a techno-thriller novel written by Tom Clancy. It focuses on John Clark, Ding Chavez, and a fictional multi-national counterterrorist unit codenamed Rainbow, rather than Jack Ryan and national politics...

, which was adapted into a successful series of tactical first-person shooter video games.
The novel Rainbow Six describes Rainbow as an international counter-terrorism operation hosted by NATO and funded by money funneled through the U.S.

"Oso backs us up, but I don't think we'll have much use for him on this trip." Julio Vega had become their heavy-machine gunner, slinging a laser-sighted M-60 7.62-mm machine gun for really serious work, but there wasn't much use for that now--and wouldn't be, unless everything went totally to hell.

Page 78

One of them came outside and lit a pipe--how very Swiss! Popov thought. The bugger probably climbs mountains for personal entertainment, too.

Page 85

Because of a random event – bad luck. A hell of a thing to tell someone who'd just lost a husband. Cause of death, bad luck.

Page 124

"Thanks, Doc." Chavez hefted the book for weight and headed out the door. The Enraged Outlook: Inside the Terrorist Mind was the title. It wouldn't hurt to understand them a little better, though he figured the best thing about the inside of a terrorist's mind was a 185-grain 10-mm hollow-point bullet entering at high speed.

Page 142

The man had to be tense, Popov knew. Betrayal was how most of the people like Fürchtner got caught, and though Dmitriy was known and trusted by them, you could only be betrayed by someone whom you trusted, a fact known to every covert operator in the world.

Pages 145-146

They were either very brave or very foolish to go to that country, Popov thought. [...] Bokassa had killed his way to the top, as had so many African chiefs of state, before dying, remarkably, of natural causes--so the papers said, anyway, you could never really be sure, could you?

Page 147

"We have thought that one through," Hans assured his guest. Popov wondered briefly about that. But he'd be surprised if they even boarded an aircraft, much less got it to Africa. The problem with "missions" like this one was that no matter how carefully most of its parts had been considered, this chain was decidedly no stronger than its weakest link, and the strength of that link was all too often determined by others, or by chance, which was even worse.

Page 148