As the critical sanctions against Iran's nuclear program demonstrate, the implementation of sanctions against nuclear proliferators has led to the creation of a global system of surveillance of the financial dealings of all states, banks, and individuals, fostered by United Nations Security Council resolutions—a new and unprecedented development. This chapter asks: Which actors have been in charge of designing and implementing sanctions against nuclear proliferators? Which legal technologies have they developed to regulate global financial transactions? Answering these questions generates a better understanding of key processes in global governance: the increasing role of the Security Council as a global legislator; the "financialization" of global regulation, with the increasing role played by international and US domestic financial institutions that were historically foreign to the field of nuclear nonproliferation; and the judicialization of the enforcement of sanctions, which is accompanied by the multiplication of secondary sanctions against sanctions-evaders.