My country (Italy) is undergoing a phase of parliamentary transition.During my tenure as foreign minister, I have made it a point to place the Mediterranean and the Middle East at the forefront of Italy’s agenda.The writer is Italy’s minister of foreign affairs and a former ambassador to Israel.This op-ed is adapted from his address to the 13th Herzliya Conference this week.Our Middle Eastern policy has long been built on a basis of coherence and continuity, principles that Italy will hold dear at any time, under any government.As my country’s new political scene takes shape, I could seize no better opportunity than this to outline the rising challenges that lie ahead.Nuclear proliferation, and particularly Iran’s nuclear ambition, is the most pressing of these challenges. Rivers of ink have been spilled on how to tackle Iran’s nuclear aspirations. The debate seems to have polarized into two main positions. According to the first one, a nuclear Iran cannot be reliably contained because there is no guarantee that it will behave rationally; therefore, it must be prevented at all costs. The second is that Iran is a rational actor, and can be deterred and contained; hence, the risks of preventing it are not warranted for.However, I would argue that a nuclear Iran must be prevented precisely because it would act rationally. Should Iran acquire a nuclear military capability, it is mainly the conventional balance of the region that would take a different shape.Under its own nuclear umbrella, Tehran would be free to raise and lower the volume of regional tension as best suits its national interest. Its range of foreign activity tools would instantly broaden, to include several destabilizing options. Increasing the tension on the Israeli-Lebanese border to make oil prices skyrocket would become a viable economic path.Arming a friendly and ruthless regime with weapons of mass destruction could become a rational course of action.With a nuclear Iran, the rules of the Middle Eastern game would not only change overnight; they would change irreversibly. As it’s been appropriately put, in the Middle East “cost benefit calculations would be replaced by risk management.”Iran’s nuclear pursuit is also a stark reminder that the general discussion on the role of nuclear weapons is in dire need of a drastic overhaul. For 50 years, we have been used to a “clean,” bipolar nuclear environment with simple, if frightening, rules. Those rules were applicable to a world where technology was scarce and out of reach for all but the superpowers, and cyber-war and nuclear terrorism simply did not exist.The main change that occurred in these rules is that today’s multi-polar nuclear order acquires a regional dimension. Nuclear dynamics are no more the tides of one “global” bilateral relationship. They are now defined not only in Washington and Moscow, but also in Beijing, Delhi, Islamabad and Pyongyang. These countries’ nuclear weapons, as would be Iran’s, could all be “aimed” at conditioning regional balances, which, in turn, interact with one another adding uncertainty and instability. Recurrent recent news of a possible nuclear dimension to the cooperation between Iran and North Korea is a troublesome reminder of this fact.In the end, however “regional” the trigger, a nuclear crisis will always have a global impact.This is why the prospect of proliferation in a region as volatile as the Middle East is so alarming. Should Tehran acquire nuclear capabilities, others would follow, and the Middle East – the very doorstep of Europe - would enter this new regional nuclear race.This trend is unfolding much faster than the discussion around it. We are largely stuck in an unrealistic cold-war conception of nuclear issues, as are the international instruments we rely upon. The NPT is the most valuable multilateral system we have. It works to a very large extent, and can be regarded as one of the most remarkable successes of diplomacy for security.And yet, a reflection on how to make it stronger and fitter for today’s world is long overdue; a reflection that acknowledges the nature and diffusion of new technologies; the threat of cyber attacks on nuclear infrastructure, and nuclear terrorism; and the regional dimension of proliferation.Ultimately, moving towards a global zero goal means pushing beyond the NPT as it is today, first by expanding and reinforcing its safeguards, and eventually through an international agreement for the abolition of nuclear weapons.At the regional level, everybody recognizes that the Middle East is a very special case. The EU, as well as other partners, also in the framework of the UN, have long advocated the creation of a nuclear-free zone. We are all well aware of the difficulties, and realism advises that we treat this goal as a long-term perspective.