The Special Relationship between the U.S. and Britain has many facets, but at its core is close cooperation in the military and intelligence realms. And at the heart of our military cooperation is the U.S.–U.K. Mutual Defence Agreement. Signed in 1958, and renewed every 10 years—most recently in 2004—the agreement provides for Anglo–American collaboration in nuclear technology. It provides the legal basis for the transfer to Britain of U.S.-made Trident II missiles—the launch platform for Britain’s nuclear deterrent—and for the much broader sharing of nuclear information between the two countries.