Since the mid-1970s, and especially since 1998, volumes have been written about nuclear weapons proliferation in Pakistan and India and the impact of this proliferation on stability and security on the Subcontinent. Other literature has focused on the manner in which decisions about strategic force structures in Pakistan, India, China and the United States connect to one another in discrete nuclear proliferation chains, driving decisions that impact an interconnected set of paired security dilemmas (Pakistan-India and India-China, India-China and China-U.S.). Over the past decade, a legion of authors and commentators have made considerable speculation about the security risks from Iran's nuclear program and the risks that program poses for crisis stability and nuclear weapons incentives in the Persian Gulf and between Iran and its Arab neighbors. This book aims to update and integrate these three areas of analysis. It updates the status of nuclear weapons proliferation and crisis stability on the Subcontinent as of early 2013. It also explores the relationship between Iran's nuclear development trajectory and pathways, discussing the interplay of Saudi Arabia and Pakistan in the context of possible responses to Iran's nuclear program endstate. It then discusses the most likely security impacts from Saudi-Pakistan interaction on nuclear weapons collaboration for South Asian nuclear stability and proliferation dynamics. Finally, it discusses the implications for American policymakers desiring to counteract the worst-case possibilities foretold by these interactions: spiraling Indo-Pakistani military crises and escalating arms races between India, China, and Pakistan on the Subcontinent.