THE next US president will have no easy policy options on Iran - attacking, accommodating or boxing it in are all fraught with risks and difficulties. Even these choices for Barack Obama or John McCain could be pre-empted if Israel exploits the last few months of President George W. Bush's term to smash Iran's nuclear facilities. Israeli Prime Minister Ehud Olmert, in his toughest warning yet to Tehran, said in Washington on Tuesday the Iranian nuclear program must be stopped by “all possible means.” Olmert urged the international community “to clarify to Iran, through drastic measures, that the repercussions of their continued pursuit of nuclear weapons will be devastating.” Israel, widely believed to have hundreds of nuclear warheads, views Iran as its deadliest threat. Tehran says its nuclear ambitions are confined to generating electricity. Even if Israel holds back, whoever wins the White House in November will face realities which dim prospects that Iranian power can be rolled back by the tactics already tried by the West: threats, sanctions, isolation and economic carrots. Iran's regional clout and nuclear ambitions have defied containment, especially since Bush removed two of its sworn foes - the Taleban in Afghanistan and Saddam Hussein in Iraq. Extending its reach, Tehran has gained undeniable influence in the Arab-Israeli conflict via its long-standing alliance with secular Syria, Shi'ite Hezbollah guerrillas in Lebanon and its newer links with the Palestinian Hamas movement. Iranian President Mahmoud Ahmadinejad, flush with windfall oil revenue, has so far overridden domestic critics of his populist economic policies, combative nuclear stance and rhetoric against the United States and the existence of Israel. Final arbiter Supreme Leader Ayatollah Ali Khamenei, the final arbiter on Iranian policy, has not reined in the radical president, who faces what could be a tough re-election battle next year. Khamenei said on Tuesday Iran would defy Western pressure in pursuit of its “peaceful” nuclear goals, a policy followed even before Ahmadinejad replaced his reformist predecessor in 2005. Continued insistence on enriching uranium also puts Iran at risk of US military action, whether the Democrat Obama or his Republican rival is in the White House, said Paul Salem, head of the Carnegie Endowment's Middle East Centre in Beirut. “The United States will attack Iran sooner or later if this goes on,” he said. “It can do it and I don't think the Iranian response, whatever it is, will deter the US in the end.” Tough talk from McCain suggests he would be at least as ready as Bush to apply US military might if economic warfare through extra sanctions fails to shift Iran's nuclear policy. Iranian reprisals could include fuelling anti-US revolts in Iraq, prompting Hezbollah to rocket Israel, disrupting Gulf oil exports or inciting unrest among Shi'ite minorities. To avoid another violent upheaval in the Middle East and its likely dire global consequences, Obama advocates engagement with Iran and other perceived US enemies such as Syria. A diplomatic approach could pay off, according to Ebrahim Yazdi, leader of Iran's banned Freedom Movement and foreign minister in the first cabinet after the 1979 Islamic revolution. “If unconditional negotiations take place, there is a great chance they will be able to come to some conclusion,” he said. Yazdi hailed Obama's stress on “global leadership, not global domination”, but said that if McCain won and Ahmadinejad was re-elected “the confrontation, the rhetoric, will continue.” Right now, prospects for a US-Iranian rapprochement, let alone a “grand bargain” to resolve nearly 30 years of hostility, seem remote in an increasingly polarized and fragmented region. Bush has sought to rally Israel and Sunni Arab states against “evil-doers” such as Iran, Syria, Hezbollah and Hamas - a contest in which small players like Lebanon get trampled. Even the tentative, low-level talks he permitted with Iran on how to stabilize postwar Iraq have stalled. Obama's diplomatic option Could an Obama presidency alter the rules of the game? “The problem is that facts on the ground in the region are changing faster than America has been able to adjust to,” said Trita Parsi, author of “Treacherous Alliance”, a recent book on dealings between Israel, Iran and the United States. Offering Iran security guarantees or accession to the World Trade Organization might have worked before, but perhaps not now when the power balance has shifted Tehran's way, he argued. Parsi said it would be very hard to persuade Iran to give up uranium enrichment or to be satisfied with much less than US recognition of its regional role - an enduring Iranian goal. “That means the Iranians would have a seat at the table on every important question in the region, so everyone else would also have to accommodate a greater Iranian role,” he said. “I'm not sure even an Obama administration would be ready for that.” Instead of adjusting to Iran's power, the United States and Israel were “pursuing the politics of miraculous hope” by mulling military action or seeking a Syrian-Israeli peace deal that would deprive Tehran of a staunch ally, Parsi said. Iran expert Karim Sadjadpour said no US-Iranian detente was likely while Ahmadinejad remained in power and no consensus existed in Iran on whether achieving one would be worthwhile. “There is a small but powerful minority among Iran's political elite who recognize that doing so would be a threat to their interests, and whenever confidence is being built between the two sides, they do their best to torpedo it,” he added. Another obstacle would be US insistence that Iran soften its hostility to Israel, which Sadjadpour said would mean giving up one of the few remaining tenets of the Islamic revolution. While the United States and Iran could gain much from strategic talks on an accommodation that might calm many of the Middle East's tensions, the gulf dividing them still yawns wide. Mutual animosity that flared over the 1979 seizure of the American embassy in Tehran has never really healed. “The US and Iran don't necessarily have conflicting interests,” Carnegie's Salem said. “They just hate each other.” – Reuters – (Additional reporting by Fredrik Dahl in Tehran) __