This chapter examines a typical marker of nuclear status — the nuclear test. Existing scholarship has shown that states bargain around nuclear tests. But the success of bargaining is premised on underlying technical ambiguities that obscure the link between nuclear testing and the constitution of nuclear statehood. Throughout the Cold War, the meaning of nuclear tests was complicated by the entanglement of civilian and military uses of technology. In particular, “peaceful nuclear explosions” (PNE) made it difficult to distinguish between nuclear and non-nuclear status because it was unclear what a PNE meant for a state’s nuclear status. Beyond the PNE, other technical ambiguities around the subcomponents of a nuclear weapon also facilitated the contestation of nuclear status. These ambiguities shaped the Israeli nuclear program and enabled the Israeli policy of amimut, or opacity. This chapter examines Israeli contestation throughout the 1960s and 1970s and the eventual settling of Israel’s nuclear status around the language of “non-introduction.”