Nuclear technology has always been a closely guarded and powerful secret component of the United States' military arsenal. With so much emphasis on secrecy of design, development, and use, the question arises as to why the United States shared submarine-launched ballistic missile (SLBM) technology with the United Kingdom. Further, how did it help the United States combat the Soviet threat during the Cold War?
The reason was simple. The British had something the Americans wanted and vice versa. The Brits wanted nuclear-tipped missiles (initially air-launched, later sea-launched), and the Americans needed bases for their Polaris submarines closer to the Soviet Union than the East Coast of the United States. And both nations were prepared to deal.