VIENNA — Diplomats say Iran is poised for a major expansion of its nuclear program at a cavernous underground site.

They have told The Associated Press that Tehran has readied the site for the installation of thousands of new-generation centrifuges. These machines could greatly speed up production of material that can be turned into the core of nuclear warheads.

The diplomats say that electrical circuitry, piping and supporting equipment for the new centrifuges is in place.

They emphasize that Tehran has not started installing the more efficient machines at its Fordow facility and cannot say whether it was planning to.

But the diplomats say Iran has little reason to prepare the ground for the better centrifuges unless it planned to operate them.

The diplomats asked for anonymity because their information is privileged.

Copyright 2012 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Subscribe to the Tribune-Review today

That is the assessment of American defense officials and military analysts close to the Pentagon, who say that an Israeli attack meant to set back Iran’s nuclear program would be a huge and highly complex operation. They describe it as far different from Israel’s “surgical” strikes on a nuclear reactor in Syria in 2007 and Iraq’s Osirak reactor in 1981.

“All the pundits who talk about ‘Oh, yeah, bomb Iran,’ it ain’t going to be that easy,” said Lt. Gen. David A. Deptula, who retired last year as the Air Force’s top intelligence official and who planned the American air campaigns in 2001 in Afghanistan and in the 1991 Gulf War.

Speculation that Israel might attack Iran has intensified in recent months as tensions between the countries have escalated. In a sign of rising American concern, Tom Donilon, the national security adviser, met with Prime Minister Benjamin Netanyahu of Israel in Jerusalem on Sunday, and the chairman of the Joint Chiefs of Staff, Gen. Martin E. Dempsey, warned on CNN that an Israeli strike on Iran right now would be “destabilizing.” Similarly, the British foreign secretary, William Hague, told the BBC that attacking Iran would not be “the wise thing” for Israel to do “at this moment.”

But while an Israeli spokesman in Washington, Lior Weintraub, said the country continued to push for tougher sanctions on Iran, he reiterated that Israel, like the United States, “is keeping all options on the table.”

The possible outlines of an Israeli attack have become a source of debate in Washington, where some analysts question whether Israel even has the military capacity to carry it off. One fear is that the United States would be sucked into finishing the job — a task that even with America’s far larger arsenal of aircraft and munitions could still take many weeks, defense analysts said. Another fear is of Iranian retaliation.

“I don’t think you’ll find anyone who’ll say, ‘Here’s how it’s going to be done — handful of planes, over an evening, in and out,’ ” said Andrew R. Hoehn, a former Pentagon official who is now director of the Rand Corporation’s Project Air Force, which does extensive research for the United States Air Force.

Michael V. Hayden, who was the director of the Central Intelligence Agency from 2006 to 2009, said flatly last month that airstrikes capable of seriously setting back Iran’s nuclear program were “beyond the capacity” of Israel, in part because of the distance that attack aircraft would have to travel and the scale of the task.

Still, a top defense official cautioned in an interview last week that “we don’t have perfect visibility” into Israel’s arsenal, let alone its military calculations. His views were echoed by Anthony H. Cordesman, an influential military analyst at the Center for Strategic and International Studies in Washington. “There are a lot of unknowns, there are a lot of potential risks, but Israel may know that those risks aren’t that serious,” he said.

Given that Israel would want to strike Iran’s four major nuclear sites — the uranium enrichment facilities at Natanz and Fordo, the heavy-water reactor at Arak and the yellowcake-conversion plant at Isfahan — military analysts say the first problem is how to get there. There are three potential routes: to the north over Turkey, to the south over Saudi Arabia or taking a central route across Jordan and Iraq.

The route over Iraq would be the most direct and likely, defense analysts say, because Iraq effectively has no air defenses and the United States, after its December withdrawal, no longer has the obligation to defend Iraqi skies. “That was a concern of the Israelis a year ago, that we would come up and intercept their aircraft if the Israelis chose to take a path across Iraq,” said a former defense official who asked for anonymity to discuss secret intelligence.

Assuming that Jordan tolerates the Israeli overflight, the next problem is distance. Israel has American-built F-15I and F-16I fighter jets that can carry bombs to the targets, but their range — depending on altitude, speed and payload — falls far short of the minimum 2,000-mile round trip. That does not include an aircraft’s “loiter time” over a target plus the potential of having to fight off attacks from Iranian missiles and planes.

Scott Shane contributed reporting.

Iran’s nuclear ambitions could plunge the world into “a new Cold War” with the Middle East, Foreign Secretary William Hague has warned.

He predicted a nuclear arms race among rival Middle Eastern states that would carry the dangers without the safety mechanisms of the old rivalry between the West and the USSR.

In an interview with The Daily Telegraph, he insisted Britain did not back military action against the Islamic republic – as Israel is thought to be planning.

But he said there was a “crisis coming down the tracks” that could result in “disaster” for world affairs.

“(The Iranians) are clearly continuing their nuclear weapons programme,” Mr Hague said.

“If they obtain nuclear weapons capability, then I think other nations across the Middle East will want to develop nuclear weapons.

“And so, the most serious round of nuclear proliferation since nuclear weapons were invented would have begun with all the destabilising effects in the Middle East. And the threat of a new Cold War in the Middle East without necessarily all the safety mechanisms. That would be a disaster in world affairs.”

There are growing fears that President Mahmoud Ahmadinejad will not be deterred by sanctions, the preferred route of the US and Britain to pressure the regime into abandoning its nuclear weapons programme.

Israel is rumoured to be planning military strikes within months. Mr Ahmadinejad claimed this week that Iran had loaded its first domestically-made fuel rod into a nuclear reactor.

Mr Hague stressed that “all options must remain on the table” concerning Iran but said that a military attack would have “enormous downsides”. He added: “We are not favouring the idea of anybody attacking Iran at the moment.”

Britain and France depend little on Iranian oil, however, so their targeting may be a mostly symbolic act, a function of the strong positions the two nations have taken in trying to halt Iranian nuclear enrichment and to bring pressure to bear on Syria, one of Iran’s closest allies.

Iran may also be reluctant, when its economy has been damaged by existing sanctions, to deprive itself of revenues from its larger European customers. At the same time, it may be seeking to divide the 27-nation European Union between those who depend on Iranian oil and those who do not.

Sunday’s order, according to the Mehr News Agency in Tehran, came from the Iranian oil minister, Rostam Qassemi, who had warned this month that Iran would cut off oil exports to “hostile” European nations. On Sunday, the Oil Ministry spokesman, Ali Reza Nikzad-Rahbar, confirmed that shipments to Britain and France had been cut off, and said on the ministry Web site, “We have our own customers and have no problem to sell and export our crude oil to new customers.”

At the same time, according to the Mehr agency, an official at the Oil Ministry said Iran was seeking longer-term contracts of two to five years with other European nations.

There was no immediate reaction from French officials, and the British Foreign Office in London declined to comment. A British government official, demanding anonymity to describe internal discussions, said that “we’re not getting exercised about it,” noting that Iran provides “less than 1 percent of our imported crude oil.”

Jean-Louis Schilansky, president of the French Union of Petroleum Industries, told the French newspaper Le Monde that “the Iranian decision has no practical, direct consequences” for France, which since 2011 “practically stopped importing Iranian oil.”

Iran is deeply dependent for foreign currency from oil sales, which supply more than 50 percent of the national budget and account for 80 percent of exports. Iran produces about 3.5 million barrels a day and exports about 2.5 million, 70 percent of that to Asia.

The 27 nations of the European Union are a big customer as a whole, representing about 18 percent of Iran’s exports.

But Britain and Germany get only about 1 percent of their oil from Iran, and France gets only about 3 percent from there. Other European countries, like Greece, Italy and Spain, are much more reliant on Iranian oil. Greece, for instance, gets about one-third of its oil from Iran, while Italy and Spain each get about 13 percent, according to European Union figures.

Greece, Italy and Spain were more reluctant than Britain, France and Germany to vote for rapid oil and banking sanctions against Iran.

Britain, France and Germany are also the European nations negotiating with Iran on its nuclear program in the talks that also include the United States, Russia and China and are presided over by the European Union’s policy chief, Catherine Ashton.

France and Britain have pushed hard to increase sanctions against Iran to get it to stop nuclear enrichment in what many in the West believe to be an Iranian program to build a nuclear weapon. The sanctions are part of a dual-track strategy that combines pressure with negotiations. Germany, however, has explicitly opposed any military action against Iran, while Britain and France, like the United States and Israel, have refused to rule out military action.

Iran denies that its nuclear program has any military intent, but it has flouted repeated Security Council resolutions requiring it to stop nuclear enrichment and cooperate fully with the International Atomic Energy Agency. Merging conciliation with threat, Iran has recently boasted that it was about to start a vast new array of centrifuges to enrich uranium deep in a mountain that would be very difficult to bomb, while it has renewed its call for negotiations after a gap of a year.

French officials believe the threat of new sanctions and the bite of older ones, together with the travails of the Syrian government and the hints of military action coming from Israel, are bringing Iran back to the table. They are concerned, however, that the Iranian offer for talks is simply another way to buy time while the centrifuges continue to turn. They also fear that if the talks fail, a military strike on Iran may follow.

Last week, Iran sent a letter to Ms. Ashton calling for a new round of negotiations with the group of six, in response to a letter from her on Oct. 17. The Iranian letter, from the country’s nuclear negotiator, Saeed Jalili, declared Iran’s “readiness for dialogue” at “the earliest possibility.” The letter, which was vague but did not contain preconditions, was greeted by Ms. Ashton and Secretary of State Hillary Rodham Clinton with a mixture of optimism and skepticism.

French officials have said that Iran must agree to talks that center on the key issue: its nuclear program and the calls by the Security Council to stop it. The last round of talks ended a year ago when Mr. Jalili demanded that the United Nations first lift all sanctions and acknowledge Iran’s “right to enrich” uranium before talks could begin. The demands were unacceptable, and the six say that the Nuclear Nonproliferation Treaty contains no “right to enrich,” only the right to peaceful nuclear energy.

The French foreign minister, Alain Juppé, said last week that the European Union would carry out its sanctions with determination. “Iran continues to develop a military nuclear program, we are convinced,” he said Wednesday. “We say to Iran that the path for dialogue remains open, but if it’s not engaged, then the sanctions will be enforced with great firmness.”

Ravi Somaiya contributed reporting from London, and Artin Afkhami from Boston.

IRAN’S nuclear ambitions could trigger “a new Cold War” more perilous than that between the West and the Soviet Union, British Foreign Secretary warned.

William Hague said Iran obtaining a nuclear bomb would spark an atomic arms race between rival Middle Eastern nations that could be more dangerous than the original Cold War because the old “safety mechanisms” are missing.

“If (the Iranians) obtain nuclear weapons capability, then I think other nations across the Middle East will want to develop nuclear weapons,” he told Britain’s Daily Telegraph newspaper.

“The most serious round of nuclear proliferation since nuclear weapons were invented would have begun with all the destabilising effects in the Middle East,” he continued.

“And the threat of a new Cold War in the Middle East without necessarily all the safety mechanisms… would be a disaster in world affairs.”

Iran faces four sets of UN sanctions and a raft of unilateral US and EU sanctions designed to halt a programme the West fears conceals a drive for nuclear weapons.

Tehran denies this charge, saying its nuclear project is for purely peaceful purposes.

In response to feverish speculation in recent weeks that Israel is preparing to mount a pre-emptive strike on Iran’s nuclear programme, Hague said Iran being “attacked militarily” would have “enormous downsides”.

“We are very clear to all concerned that we are not advocating military action,” he told the Telegraph.

“We support a twin-track strategy of sanctions and pressure and negotiations on the other hand.”

“We are not favouring the idea of anybody attacking Iran at the moment,” he added.”

Earlier Friday, US Secretary of State Hillary Clinton and the European Union’s foreign policy chief Catherine Ashton voiced cautious optimism about the prospect for Iran to return to stalled nuclear talks with six world powers.

In a February 14 letter to Ashton, Iran’s chief nuclear negotiator Saeed Jalili said Tehran is ready to resume talks at the “earliest” opportunity as long as the six powers respect its right to peaceful atomic energy.

kjl/pvh