Does Israel have the military might to end Iran's nuclear ambitions? Iran-watchers are inclined to dismiss outbursts of this kind as mere rhetorical flourishes. Inflammatory phrases provide no guide to the regime's real intentions, they say. Judge the Ayatollah by his cautious actions and modest capabilities, not his speeches. They could be right, but Israelis do not see it that way. When a national leader threatens them with annihilation, they are inclined to take him seriously - and given the history of the 20th century, who can blame them? Outsiders find it hard to grasp how Iran's nuclear ambitions stir something deep within the soul of Israel. This country's founding purpose was to provide a haven for the Jewish people. When another state threatens Israelis with destruction, while pursuing a nuclear programme that might just provide the tools for the job, they are more fearful than citizens of placid lands can easily understand. And that leads to the next instinctive reaction. Israelis believe they can trust no one - not even the United States - with their own security. In the end, they will insist on taking their own decisions on how to counter any threat. Benjamin Netanyahu, the prime minister, pointedly reminded President Barack Obama in the White House in March that Israel must remain the "master of its fate." But trusting others is exactly what Israel is now being called upon to do. If the talks with Iran succeed in resolving the nuclear question, Israel will have to decide whether it can live with a deal negotiated by the six favoured countries. Perhaps unwisely, Mr Netanyahu has spelt out the terms of an agreement he would find acceptable: Iran must stop enriching uranium, surrender the entirety of its existing stockpile and dismantle the facility at Fordow where this process has been taking place in a bunker dug into a mountainside. But he is setting himself up for a fall: any realistic settlement would almost certainly fall short of those demands. Privately, Western officials say that a viable deal would allow Iran to continue enriching uranium, albeit with the strictest safeguards. The goal is to "restore international confidence" in Iran's nuclear programme, not raze this effort to the ground. Quietly, the negotiations are moving towards a formula that would allow Tehran to enrich uranium, while giving the rest of the world enough assurance that this process would only be used to make fuel for nuclear power stations, not the fissile core of a weapon. Some retired officials, notably Peter Jenkins, Britain's former ambassador to the International Atomic Energy Agency, have said in public that "enrichment plus safeguards" is the only way out of the labyrinth. But could Israel accept such an outcome? In the end, Mr Netanyahu may have little choice. Some good judges, including Michael Hayden, a former CIA director, believe that his threat of war is a bluff. Israel may lack the military ability to destroy Iran's nuclear facilities. Doing the job would require most - if not all - of the air force's 125 F-15 and F-16 strike aircraft to attack a range of targets between 900 and 1,200 miles from their home base. Airborne refuelling would be the key requirement - yet, on paper, Israel has only seven tanker planes. Could they get the bombers and their fighter escorts all the way to Iran and back again? Few countries can match Israel for military ingenuity; perhaps Mr Netanyahu has cards up his sleeve that no one knows of. But there is a real possibility that wrecking Iran's nuclear plants is beyond his reach. Even if the goal was achievable, he would still have to weigh the central objection to war: Iran could rebuild its key installations, meaning that any air strikes would delay but not derail its nuclear ambitions. The most that Israel could achieve would be to buy time - and perhaps not very much time at that. Mr Netanyahu might end up precipitating a global crisis for the sake of setting back Iran's programme by only a handful of years. As he wrestles with this dilemma, he remains a key actor in this drama. Whenever the six countries negotiate with Iran, an absent Israel has the power to upset every calculation.