Ahead of Prime Minister Binyamin Netanyahu's trip to Washington this week, the US has been urging Israel to "tone down" its rhetoric on Iran and to stop threatening a military strike on its nuclear installations, The Jerusalem Post has learned. This was one of the purposes of a secret trip to Israel three weeks ago by CIA Director Leon Panetta, foreign diplomatic sources said. Ostensibly, the CIA chief came to share information on Iran's nuclear program with Israeli intelligence officials and find out how serious the new Israeli government was in its stated position that Jerusalem cannot allow Iran to become a nuclear power. Panetta was hosted by Mossad chief Meir Dagan and intelligence officials, but also met with Netanyahu and Defense Minister Ehud Barak. While the Obama administration is intent on spearheading an international campaign to prevent Teheran from building nuclear weapons and believes that a nuclear Iran would pose a threat to the stability of the Middle East, US officials - led by Undersecretary of State for Political Affairs William Burns - plan to offer Iranian leaders a new approach and a return to the international fold in exchange for freezing their nuclear program. One official said, however, that while the administration's policy was a risk worth taking, it could fail and it might be necessary for the US and its allies to accept the fact of a nuclear Iran. In either scenario, they said, both the US and Israel should refrain from any bellicose threats against the Islamic Republic, especially ahead of its presidential elections on June 12. Asked about the Iranian nuclear threat in an interview on Channel 2 on Saturday, Barak said Israel was "not taking any option off the table, and we suggest everyone else do the same." While surveys taken recently in Iran have indicated that President Mahmoud Ahmadinejad is favored to win another term, opposition to his extremist positions - especially regarding Israel, Egypt and the rest of the Arab world and his recent strengthening of its ties with Syria - has grown significantly, intelligence officials said. Diplomatic officials said military threats on Iran from Israeli officials at this time would only strengthen Ahmadinejad and encourage the Iranian regime to speed up its acquisition of nuclear technology with help from North Korea and perhaps even Russia. The US took great care to keep the trip of the CIA chief under wraps, although Israeli officials leaked some details of his talks to Israel Radio late last week. The leak came after Iranian army chief Ataollah Salehi made the most explicit threat yet against Israel in a speech earlier this month. In a May 3 speech broadcast on LBC television and translated by MEMRI, he said: "Nothing can prevent Iranian missiles from targeting the heart of Israel if Iran is subjected to a military strike by Israel. "This was the response of the Iranian military commanders to the Israeli statements about a possible military strike against Iran, because of its insistence on obtaining nuclear energy. Yet an [Israeli] attack seems improbable to the Iranians, because Tel Aviv does not have the ability to go through a war with Teheran," he said. "We are fully prepared to confront any attack that would threaten the interests of Iran. We have sufficient means and the necessary force to defend our territory," he added. "The truth is that Israel does not have the courage to attack us. If we are subjected to any attack by Israel, I do not think we will need more than 11 days to wipe Israel out of existence." The US has urged Israeli officials to refrain from responding directly to the comments, to avoid a new exchange of mutual threats between Teheran and Jerusalem. All Israeli spokesmen approached for a response declined to give one. A US official argued that a report in The Times in Britain last month quoting an Israeli official as saying Israel could be ready in days or weeks to strike Iran caused considerable damage to American efforts to establish a dialogue with Teheran, and speculated that the Iranian army chief's comments were probably made in response to that report. The Times's Jerusalem correspondent, Sheera Frenkel, reported that "the Israeli military is preparing itself to launch a massive aerial assault on Iran's nuclear facilities within days of being given the go-ahead by its new government. "Israel wants to know that if its forces were given the green light they could strike at Iran in a matter of days, even hours. They are making preparations on every level for this eventuality. The message to Iran is that the threat is not just words," a senior defense official was quoted as telling The Times. Despite Obama's initial plan to open a dialogue with Iran as soon as possible, US officials said the talks would probably not take place until after the Iranian elections in June, and would include the participation of Russia, China and the European Union. They said the aim would be to form a united international front to press the Iranians to abandon their uranium enrichment program and their quest for nuclear weapons. The US has, for now, rejected Israel's request that it set a time frame for the Iranian dialogue. US National Security Council spokesman Mike Hammer told foreign journalists recently that "it's not appropriate at this time to be trying to establish timetables, but rather seeing how the engagement can move forward." "We are in a process that we expect will take some time," Hammer said. "We've had a difficult - at best - relationship in the past with Iran, and we're looking to see what is possible."