Among the steps taken to ready Israeli forces for what would be a risky raid requiring pinpoint aerial strikes are the acquisition of three Airborne Warning and Control (AWAC) aircraft and regional missions to simulate the attack.

Two nationwide civil defence drills will help to prepare the public for the retaliation that Israel could face.

“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,” one senior defence official told The Times.

Officials believe that Israel could be required to hit more than a dozen targets, including moving convoys. The sites include Natanz, where thousands of centrifuges produce enriched uranium; Esfahan, where 250 tonnes of gas is stored in tunnels; and Arak, where a heavy water reactor produces plutonium.

The distance from Israel to at least one of the sites is more than 870 miles, a distance that the Israeli force practised covering in a training exercise last year that involved F15 and F16 jets, helicopters and refuelling tankers.

The possible Israeli strike on Iran has drawn comparisons to its attack on the Osirak nuclear facility near Baghdad in 1981. That strike, which destroyed the facility in under 100 seconds, was completed without Israeli losses and checked Iraqi ambitions for a nuclear weapons programme.

“We would not make the threat [against Iran] without the force to back it. There has been a recent move, a number of on-the-ground preparations, that indicate Israel's willingness to act,” said another official from Israel's intelligence community.

He added that it was unlikely that Israel would carry out the attack without receiving at least tacit approval from America, which has struck a more reconciliatory tone in dealing with Iran under its new administration.

An Israeli attack on Iran would entail flying over Jordanian and Iraqi airspace, where US forces have a strong presence.

Ephraim Kam, the deputy director of the Institute for National Security Studies, said it was unlikely that the Americans would approve an attack.

“The American defence establishment is unsure that the operation will be successful. And the results of the operation would only delay Iran's programme by two to four years,” he said.

A visit by President Obama to Israel in June is expected to coincide with the national elections in Iran — timing that would allow the US Administration to re-evaluate diplomatic resolutions with Iran before hearing the Israeli position.

“Many of the leaks or statements made by Israeli leaders and military commanders are meant for deterrence. The message is that if [the international community] is unable to solve the problem they need to take into account that we will solve it our way,” Mr Kam said.

Among recent preparations by the airforce was the Israeli attack of a weapons convoy in Sudan bound for militants in the Gaza Strip.

“Sudan was practice for the Israeli forces on a long-range attack,” Ronen Bergman, the author of The Secret War with Iran, said. “They wanted to see how they handled the transfer of information, hitting a moving target ... In that sense it was a rehearsal.”

Israel has made public its intention to hold the largest-ever nationwide drill next month.

Colonel Hilik Sofer told Haaretz, a daily Israeli newspaper, that the drill would “train for a reality in which during war missiles can fall on any part of the country without warning ... We want the citizens to understand that war can happen tomorrow morning”.

Israel will conduct an exercise with US forces to test the ability of Arrow, its US-funded missile defence system. The exercise would test whether the system could intercept missiles launched at Israel.

“Israel has made it clear that it will not tolerate the threat of a nuclear Iran. According to Israeli Intelligence they will have the bomb within two years ... Once they have a bomb it will be too late, and Israel will have no choice to strike — with or without America,” an official from the Israeli Defence Ministry said.

Mr Chavez's office was quick to distribute a picture of the pair smiling and clasping hands during the encounter, which came shortly after regional leaders arrived for the 34-nation summit.

The Venezuelan leader's office said that he wanted things to change between their two nations. "I want to be your friend," Mr Chavez told his counterpart.

The move came as Mr Obama also announced he was seeking a "new beginning" with Cuba, and was willing to work with its government on issues ranging from human rights to migration and the economy.

The cordial encounter comes as a surprise after Mr Chavez's recent criticism of the US leader. At an international conference in Doha earlier this month, he said of US policy: “It’s a policy of permanent aggression, of war, of terrorism by the US empire. That's the great guilty one, the great Satan."

He also has been critical of Mr Obama, including calling him “ignorant" last month. In addition, the leaders had a fresh stand-off on Thursday night, when the Venezuelan leader said he would veto the draft declaration of the summit over US policy towards Cuba.

Shortly after that announcement, White House officials said there would be no one-on-one meeting between the pair during the weekend summit. However, Press Secretary Robin Gibbs later said that, if Mr Chavez tapped Mr Obama on the shoulder, they would have a conversation.

Despite apparent hostility towards the US, Mr Chavez's public stance on Mr Obama varies frequently and he has also spoken of his openness to talks and an improvement in relations with the new administration.

Mr Obama, for his part, has spoken of his desire to reach out to a region neglected during eight years of US preoccupation with the War on Terror. Fred Lash, a State Department official, told The Times that the US "wanted to listen, to evaluate what others have to say as opposed to us going in with an agenda".

Whether the encounter between the pair will forestall harsh words during meetings between 34 leaders over the weekend remains to be seen.

Cuba remains a key issue of contention with leaders speaking at the opening ceremony demanding a complete lifting of the US embargo.

However, Mr Obama reiterated his desire to improve relations with Havana. "I know there is a longer journey that must be travelled in overcoming decades of mistrust, but there are critical steps we can take toward a new day," he said.

“People are scared now. They're afraid to go to mosques, afraid to make donations ... there's a general fear of anxiety and a general feeling of anger and mistrust in the Muslim community, because there's been damage between the FBI and the Muslim community,” said Munira Syeda, communications director for the Council on American Islamic Relations (CAIR).

On March 29, CAIR will conduct a “Know Your Rights” workshop in conjunction with local mosques to help ease fears and tensions throughout the Muslim community. After the incident, CAIR issued a call for people to report any kind of harassment or intimidation by FBI agents. So far, Ms. Syeda said, it has received quite a number of complaints from members saying that they were approached and questioned by the FBI.

“If the FBI does not accord fair and equitable treatment to every American Muslim organization, including CAIR, ISNA (Islamic Society of North America) and NAIT (North American Islamic Trust), then Muslim organizations, mosques and individuals will have no choice but to consider suspending all outreach activities with FBI offices, agents and other personnel,” said the American Muslim Taskforce on Civil Rights and Elections, a coalition of national Islamic organizations, in a written statement.

The Final Call reached out to Lourdes Arocho, public affairs coordinator for the FBI's Los Angeles office for an interview but was unable to obtain a response by press time.

According to Ms. Syeda, CAIR received reports that Craig Monteilh, a convicted criminal, was sent by the FBI into several California mosques, including the Islamic Center of Irvine, where he “converted” to Islam.

During the six to eight months there, he started to change his clothing to Muslim attire, then to Middle Eastern-type clothing, and began making violent statements about planning a terrorist attack to some community members.

“He was talking about America not being very good with ‘our brothers and sisters' overseas and ‘We needed to do something about it,'” Ms. Syeda told The Final Call. Then Mr. Monteilh later befriended two worshippers at the Irvine mosque and made the same violent statements to them, which they reported to local law enforcement and the FBI, she continued.

“We actually got a restraining order against him. CAIR contacted the FBI and for a number of months we did not hear anything from them. We reported a suspected criminal, a threat, but the FBI kept saying it's an open investigation and we can't talk about it,” Ms. Syeda said.

That was in 2007.

According to CAIR, the FBI also tried to recruit Ahmadullah Niazi, one of those who reported Mr. Monteilh's statements, to become an informant and when he refused, an agent threatened to make his life “a living hell.”

Then on Feb. 20, the FBI arrested Mr. Niazi, claiming that he lied about his citizenship and passport documents. He was released on $500,000 bail and has a pre-trial hearing set for April 6, according to Ms. Syeda.

“They arrested him but the interesting thing is the FBI is claiming that he has a brother-in-law who's a terrorist who supposedly worked for Osama Bin Laden, although all charges are immigration-related. He's not arrested with any terrorism-related charges,” Ms. Syeda said.

CAIR believes that the Afghanistan immigrant was targeted as retaliation for refusing to become an FBI informant. Thus far, the organization is unaware of anyone else in the Muslim community who has been arrested or is facing any charges.

Reports indicate that Mr. Monteilh, who went undercover as Frederick Jordan, according to an FBI agent's court testimony, stopped working as an FBI informant shortly after the Islamic Center of Irvine complained about him. According to the San Francisco Chronicle, since then, Mr. Monteilh has spent eight months in prison on a grand theft charge in connection with another informant job he worked for a narcotics program.

“The FBI trusted this kind of guy, who had a history of lying and cheating, with issues of national security ... We actually help support law enforcement's efforts and try to cooperate in our nation's fight against terrorism and still we're being scapegoated and treated as suspects. The concern that the Muslim community has is we cannot be partners with law enforcement, yet be suspects at the very same time,” Ms. Syeda said.

One of the two protesters escorted out of the conference hall managed to throw a red clown's nose at the Iranian president, as they yelled "racist, racist" as he stood at the podium.

Mr Ahmadinejad, the only major leader to attend the conference, said Jewish migrants from Europe and the United States had been sent to the Middle East after World War II "in order to establish a racist government in the occupied Palestine".

He continued, through an interpreter: "And in fact, in compensation for the dire consequences of racism in Europe, they helped bring to power the most cruel and repressive racist regime in Palestine."

French Ambassador Jean-Baptiste Mattei said: "As soon as he started to address the question of the Jewish people and Israel, we had no reason to stay in the room," the Associated Press news agency reported.

He continued, through an interpreter: "And in fact, in compensation for the dire consequences of racism in Europe, they helped bring to power the most cruel and repressive racist regime in Palestine."

French Ambassador Jean-Baptiste Mattei said: "As soon as he started to address the question of the Jewish people and Israel, we had no reason to stay in the room," the Associated Press news agency reported.

British Ambassador Peter Gooderham, also among those who left, said "such inflammatory rhetoric has no place whatsoever in a United Nations conference addressing the whole issue of racism and how to address it."

Speaking to the BBC Radio 4's PM programme, he said of the Iranian leader's accusation of Israeli racism: "That is a charge we unreservedly condemn and so we had no hesitation at that point in leaving the conference hall."

The US, Israel, Canada, Australia, Germany, Italy, the Netherlands, Poland and New Zealand had all boycotted the conference being held in Geneva, in protest at Mr Ahmadinejad's appearance.

His comments were described as "an absolute disgrace" by Israeli President Shimon Peres, attending a Holocaust Remembrance Day event in Jerusalem.

Israel had earlier recalled its ambassador to Switzerland.

Mr Ahmadinejad told a press conference after his speech that the countries boycotting the forum were showing "arrogance and selfishness".

Speaking at UN headquarters in New York, he said: "We call on the Iranian leadership to show much measured, moderate, honest and constructive rhetoric when dealing with issues in the region, and not this type of vile, hateful, inciteful speech."

French Foreign Minister Bernard Kouchner had warned that French delegates would walk out if the forum was used as a platform to attack Israel.

Speaking after the walkout, he said: "The defence of human rights and the fight against all types of racism are too important for the United Nations not to unite against all forms of hate speech, against all perversion of this message.

"Faced with attitudes like that which the Iranian president has just adopted, no compromise is possible."

UN Secretary General Ban Ki-moon has expressed dismay at the boycotts and the speech, saying Mr Ahmadinejad had used his speech "to accuse, divide and even incite".