Despite the focus on the dramatic political change taking place in the Middle East, Tehran's barely hidden drive toward nuclear weapons remains justifiably high on the international agenda. Iran's nuclear efforts and lack of cooperation with IAEA inspectors have led to international and unilateral sanctions, innumerable diplomatic discussions, and a near-constant flow of op-eds. Much of the debate, however, has examined Iran's nuclear potential in binary terms; either Iran will have nuclear weapons or it won't.
The manufacture and deployment of a nuclear weapon ("unacceptable," according to President Obama) would be an obvious violation of Iran's obligations under the Nuclear Non-proliferation Treaty (NPT), and would subject the country to harsher punitive measures than it currently faces.
Abandoning its nuclear weapons efforts, though decreasingly likely, would include cessation of Iran's entirely superfluous uranium enrichment activities and compliance with the transparency requirements of the NPT.
Rarely raised is a third possibility: that Iran will pursue the "Japanese option" of becoming and remaining a nuclear threshold state. Japan is widely acknowledged to have both the technological ability and the stockpile of plutonium (the by-product of its peaceful nuclear energy generation) required to produce over 1,000 nuclear weapons (by comparison, China is estimated to have around 175). The saying goes that Japan is just a "screw-turn" away from being a nuclear armed state, but for historical, ideological and political reasons, as well as because of its comprehensive defense agreement with the United States, it has chosen not to turn the screw. Japan thus remains comfortably at the nuclear threshold, enjoying the legitimacy conferred by nuclear transparency, while knowing that, if needed, nuclear weapons are well within reach.
Iran, though currently far from transparent, and with a record of nuclear obfuscation, might be pursuing a technically similar path, opening some of its facilities to observers, while developing the technology and infrastructure needed to field and deliver nuclear weapons within months, but not planning to take that last step. The threshold is not a single point; depending on a state's progress to date, it includes a variety of activities that could be completed in anywhere from days to months. Regardless of whether Iran is at the threshold, a nuclear weapon could be little more than a decision away.
In some ways the nebulousness inherent in Iran remaining a threshold state threatens to put the US as well as its Middle Eastern allies in a tougher spot than would be the case if Iran unmistakably developed nuclear weapons. Such a situation could nevertheless strengthen domestic support for and enhance the regional and international prestige of the Iranian regime, making efforts to influence or undermine it more difficult.
