US-Israeli relations have turned increasingly sour over how to deal with Iran\'s nuclear programme. But that\'s not the sole bone of contention, and contrary to the widespread assumption it\'s not a new phenomenon. Right from the start it didn\'t click between President Barack Obama and Israeli Prime Minister Benjamin Netanyahu. Shortly after becoming president, Obama urged Netanyahu to stop building new settlements in the West Bank. The prime minister didn\'t heed the new president\'s demand and things certainly didn\'t get better after that first kerfuffle. By now stories about the duo\'s icy relationship are legend. Perhaps the most telling one involves a widely reported incident last year when French President Nicolas Sarkozy told his American counterpart, not knowing that microphones were on, that he couldn\'t stand Netanyahu and that \"he\'s a liar.\" To which Obama replied, \"You are fed up with him, but me, I have to deal with him every day.\"    \"I think there is a high degree of mistrust between the two leaders,\" says James Davis, professor of international relations at the University of St. Gallen in Switzerland, about the pair. But the lack in personal chemistry between Obama and Netanyahu comes coupled with deep divisions about policy.   \"The Obama presidency originally started with the policy of engagement which Israel was very critical of and which was basically seen as appeasement of American enemies,\" notes Efraim Inbar, the director of the Begin-Sadat Center for Strategic Studies (BESA) at Bar-Ilan-University in Israel. From the perspective of many in Israel, trying to engage Iran and Syria was doomed from the get-go, says Inbar. He believes the Obama administration\'s efforts to jump-start the peace process between Israelis and Palestinians showed right away Barack Obama\'s lack of perspective and experience on Middle Eastern issues. \"The president was somewhat naïve in trying to bring about an agreement between the two sides which of course didn\'t work.\" What looks like the naïveté of an untested new president from an Israeli perspective, appears from an American vantage point like a hard-boiled power player who doesn\'t want to give an inch.           The reasons why Obama doesn\'t trust Netanyahu are numerous, says Davis, but a major reason is the Israeli settlements “where the United States has been demanding that settlement construction stop in the West Bank and it\'s preceded apace. The United States has asked Netanyahu to put a halt to settlements in East Jerusalem, but that continued apace.” The Iran issue thus only added another layer to the already existing pile of disagreements. Interestingly the discrepancy between the Obama administration and the Israeli is not about the evaluation of the Iranian nuclear programme. Both pretty much agree in their analysis about Tehran\'s progress toward a building a nuclear weapon. They core of the disagreement lies as Inbar puts it in a diverging \"threat perception\" and whether, as Israel maintains, time is running out to stop Iran before its nuclear developments are beyond the reach of destruction by outside intervention. The key question then in terms of Israeli-US relations is what will happen if Israel makes good on its claim to go it alone and strike Iranian nuclear facilities because it deems it necessary for its security. Could that be the final straw that leads to the unraveling of a relationship marked already by deep personal distrust and disparate political views? It depends, say the experts. \"It\'s going to be a function of whether the Israelis succeed,\" argues Davis. \"If the Israelis were successful in striking these facilities and in prohibiting or deterring some sort of a massive retaliatory attack everyone would be quite happy.\" Inbar agrees: \"If this attack is successful I doubt very much that the Obama administration, especially in an election year, will try to punish Israel in any way. Actually, most Americans will clap in private, some in public in the administration, and will go ahead with their regular business.\" If, however, an Israeli attack goes terribly wrong or creates huge economic, political or security fallout, then bilateral ties could test new lows, but would likely recover after a hiatus. Strange as it may seem, especially after the recent Bush era: Strong disagreements between the US and Israel in the past were, if not the norm, then certainly nothing unusual.    \"I think we\'re clouded a bit in our understanding of the relationship between Israel and the United States at the political level by the past decade or perhaps 15 years where it seemed as if the Israeli and the American political leadership were playing from the same score,\" says Davis. It wasn\'t always so cozy, explains Davis: \"There were very difficult relations between Menachem Begin for example and President Jimmy Carter. And the relationship between Golda Meir and American presidents was also not always harmonious.\" With that history in mind, could the Obama administration use its considerable leverage via financial and military aid to pressure Israel into holding off on a unilateral attack? No, says Inbar. \"We have done so in the past in 1981 (Israeli strike versus the Osirak nuclear reactor in Iraq, the ed.) without American permission, we\'ve done it in 2007 in the Syrian reactor case, so I don\'t think the Israeli leadership on issues that are so important to its national security will need permission from the United States.\"