There are five of them. They are known as "Five Eyes". I call them the Anglosphere. They are the U.S., the U.K., Canada, Australia, and recently readmitted New Zealand. "Five Eyes" refers to an agreement between the U.S. and the U.K. that stems from World War II. Subsequently extended to the other three countries, it was an agreement to share intelligence, especially signals intelligence. Informally, it was agreed not to spy on each other.
In 2010 I wrote an article for the French journal "Commentaire" on the attempt by the erstwhile Director of National Intelligence, Adm. Dennis Blair, to extend a "no-spy agreement" beyond the Five Eyes to France. Blair seems to have concluded that other major Western allies should be included in such an agreement. His onward intention was to extend such an agreement to Germany. However, Blair proposed to put the agreement with the French in writing, whereas within Five Eyes there was nothing in writing about not spying on each other.
Blair made his proposal on France after the then French President, Nicolas Sarkozy, had turned French-American relations around, presumably for good. Sarkozy had thrown himself at the feet of the U.S. Congress when he declared before that body on November 7, 2007, "I want to be your friend".
But in the final analysis the White House turned down Blair's proposal, presumably thinking that a future French Government might not be quite as pro-American as M. Sarkozy's was.
All this seems jarringly out of synch with the revelations by the defector Edward Snowden about the U.S. spying on European allies and even the European Union. François Hollande, the current French President, has been the most vociferous of the European allies in condemning this U.S. practice.