The chapter argues that Articles I & II of the NPT represent the core of the parties’ commitments as they prohibit the transfer and the receipt of nuclear weapons. U.S.–Soviet cooperation played an essential role in negotiating these articles of NPT. The main stumbling block in the negotiation process was the proposed concept of multilateral nuclear forces, which the Soviet Union regarded as unacceptable. Eventually the two sides appeared to have agreed to disagree on the NATO nuclear sharing arrangements, which are, in essence, the reduced version of MLF. The author posits that the conflict over the key articles of the NPT, I and II, will continue unabated and perhaps will even worsen as relations between the United States and Russia remain strained and maybe even worsen. The issue of nuclear sharing is hardly the most visible or fundamental challenge to the stability of the nuclear nonproliferation regime. Yet, it concerns the core obligations under the Treaty and, combined with other, more acute challenges, could present a problem, especially since conditions for cooperation and the willingness to compromise are virtually absent.