Western hopes that Iran will moderate and “engage” with the international community following the faulty 2015 nuclear agreement (JCPOA) have been gradually replaced with apprehension. More voices in the international community are joining Israel in expressing growing concern about Iran’s policies.While Iran seems to be abide by the JCPOA, it resists expanding the scope of inspections, continues its nuclear research and development (for example upgrading centrifuges) and continues to make progress on its long-range missile program. Recently it conducted a test of a missile designed to carry nuclear warheads.Moreover, Iran’s involvement in the region attests to its hegemonic plans, defying the notion, propagated by its propagandists, that it is a status quo power acting defensively. Rather, Iran is following its Persian imperial instincts that are reinforced by Muslim jihadist impulses. It already controls four Arab capitals: Baghdad, Beirut, Damascus and Sanaa; its Shi’ite militias and proxies are fighting in Iraq, Syria and Yemen and engaging in ethnic cleansing; and it is on the verge of solidifying the Shi’ite corridor from the Persian Gulf to the Mediterranean. Israel tries to capitalize on the new widespread global apprehension about Iran and a new American president who is not committed to the JCPOA to bring about the cancellation of the 2015 nuclear accord or its renegotiation, and the reinstating of the sanctions regime. Yet, these goals are difficult to attain and not useful in preventing a nuclear Iran.The international community, including the US, has little appetite to confront Iran. The belligerent tone of President Donald Trump might be pleasant to Israeli ears, but we should not forget that he has not yet dismantled the North Korean nuclear arsenal. Understanding very well the Western reluctance to take military action, Iran is emulating the North Korean scenario.Many states, Germany for example, were eager to renew business relations with Iran after the removal of the sanctions regime and to turn a blind eye to Iranian purchases of dual-use equipment.The world seems to prefer to wait until the agreement expires in 10 years or so without worrying about what will happen after. Iran signed the deal to gain legitimacy for its nuclear program without giving up the plan to go nuclear in the near future. Iran, with its thousands of years of history, is patient, seeing the agreement as only a short delay on the road to achieving its ambitions.Israel cannot rely on the international community to stop Iran’s nuclearization. Unilateral cancellation of the nuclear agreement will only energize the Iranian nuclear program. Even if attempts to convince Iran to renegotiate the deal are successful, the Iranian talent for bargaining will prolong the negotiations for years, gaining it additional time to enhance its nuclear program.Similarly, putting in place a tough economic sanctions regime requires years of diplomatic struggle. Neither Russia nor China have a great interest in helping the US neutralize the trouble potential of an anti-American Iran. Moreover, the effectiveness of economic sanctions is limited. Past sanctions were useful in bringing Iran back to the negotiating table, but not in changing its policy.The claim that a tougher deal could have been achieved in 2015 and therefore renegotiations could elicit a better one for the West is not credible. The JCPOA, with its loopholes, was the only agreement the Iranians were ready to sign when it became clear that the US under president Barack Obama would anyway be unwilling to use the military option.Despite the anti-Iranian rhetoric, the US under President Donald Trump seems to lack the strategic acumen needed to stop Iran from attaining regional hegemony. As a matter of fact, its Middle Eastern policies suit Iran.Trump continued the obsession with Islamic State (an anti-Iranian force) and is going along with the Russian and Iranian plans in Syria. The US prefers the integrity of Iraq, an Iranian satellite, rather than supporting a Kurdish state that Iran opposes. The US did not side clearly with Saudi Arabia in isolating a Qatar that courts Iran. A nuclear Iran will be even more difficult to restrain.Nothing in the world can convince Iran to give up the nuclear dream. Only the use of force can stop Iran from fulfilling its ambitions. Israel is on its own in this. Nobody will deal with an Iran that is going nuclear. Therefore, Israel must prepare its military for a strike against the main components of Iran’s nuclear infrastructure. This will not be easily achieved, but with determination and creativity it is feasible.A successful attack on Iran’s nuclear infrastructure would change the regional power equation and reverse Iranian advances. Most states would be happy for Israel to do the dirty work, and judging from past Israeli strikes on the Iraqi and Syrian reactors, would hardly create any difficulties for Israel on this account.It is true that Iran has ways to retaliate and exact costs from Israel. However, these would be easier to bear than the cost of allowing Iran to have nuclear weapons.The author is president of the Jerusalem Institute for Strategic Studies (JISS), Israel’s new conservative security think tank. He is professor emeritus at Bar-Ilan University and a fellow at the Middle East Forum.