Israeli Prime Minister Benjamin Netanyahu claimed last week that new second-generation centrifuges, which Iran plans to start up at its Natanz uranium enrichment facility, could cut by a third the time needed to create a nuclear bomb – underlining his deadline of this summer to take military action against Iran.

Netanyahu’s prediction, however, appears to be based on some unsubstantiated assumptions regarding Iranian intentions and capabilities. Yet it can provide ammunition to the hawks in Washington and Jerusalem, who could rush us into another needless and counterproductive war in the Middle East. Netanyahu’s assertions do not stand up to technical scrutiny.

Critically, he does not mention that Iran has been converting part of its 20-percent-enriched uranium hexafluoride gaseous stockpile into metallic form, for use as fuel for the Tehran Research Reactor. This conversion essentially freezes the enrichment level and subtracts from the “enrichable” gaseous stockpile used in centrifuges. It is not something that a nation hell-bent on weaponization would do.

Neglecting this fact in coming up with a hypothetical “time line to a bomb” is like balancing your bank account by registering just your income – but failing to subtract the amounts of the checks you’ve written.

Basically, whatever amount is converted to metal oxide form is not easily available for further enrichment to weapons-grade uranium, even if Iran decided to launch a weaponization effort in the future. Reconversion back to gaseous form is difficult and time-consuming and a major roadblock if a country intends to “race to the bomb.”

In addition, it is known that the Iranians are experiencing technical problems in converting their gaseous 20-percent-enriched uranium hexafluoride stockpile into metal fuel plates. If the world powers and the International Atomic Energy Agency are concerned and want to secure Iran’s enriched uranium stockpile, one way would be to offer Iran technical assistance with this conversion. This sort of technical help is a normal part of the IAEA’s official duties in member nations.

Alternatively, the world powers negotiating with Iran could agree to implement a simultaneous exchange of Iranian enriched uranium gas for foreign-produced metallic fuel plates. Indeed, if Iran received sufficient assistance with this exchange it would end up quickly retreating from the various artificial weaponization “red lines.”

Another error Netanyahu makes in his flawed time line is assuming that Iran could instantaneously install, debug and run thousands of centrifuges at full capacity. This is highly unlikely. There are almost 12,700 first-generation (IR-1) centrifuges spinning at Natanz. Installing and starting up 3,000 or so of the new second-generation (IR-2) machines will take months. It is akin to setting up a whole new facility. The latest IAEA report on Iran indicates they have installed – but not yet hooked-up ‑ just 180 of the IR-2 machines. It is not clear that they will be connected in the foreseeable future or even if they will work.

A host of engineering teething-problems are sure to ensue in starting up new centrifuge cascades; it is inconceivable that the cascades would immediately be run at full speed. Theoretically, the IR-2s work about three times faster than the IR-1s but it could take months or even years to realize the full potential of the second-generation centrifuges.

The IR-2s would be a small step up for Iran. They are not some kind of quantum breakthrough. Even the new IR-2 machines are very old 1970-80s technology by Western standards.

And by installing any additional enrichment capacity, Iran is not doing anything that violates its legal right to develop nuclear technology. Russian Foreign Minister Sergey Lavrov has been insisting on this.

“We were told by the IAEA,” Lavrov recently said in Moscow, “that they [the Iranians] will install next-generation centrifuges.” He added, “However, [Iran] is doing everything in line with their commitments under the Safeguards Agreement.”

The issue that the world powers have with Iran is a political one, not a legal one. “The IAEA will be there and will supervise this,” Lavrov said, “but I’d like to repeat that this is a legal aspect of the matter, while the political aspect is that we, along with the other Security Council members, have called on Iran to freeze enrichment operations during the negotiations.”

A recent Washington Post article said Iran is planning to build 50,000 new IR-1 centrifuges – based largely on an inquiry someone in Iran made about possibly purchasing commonplace magnets. But, as I argue in the Bulletin of the Atomic Scientists, this thesis can be called into question. A December Associated Press account that Iran was doing research on nuclear bombs was also inaccurate, as explained in a piece I co-authored for WMD Junction of The Nonproliferation Review. AP has recently published an article laying out the inconsistencies of their original story.

The best intelligence about Iran’s nuclear program indicates that no nuclear weapons work is going on in Iran right now. James Clapper, the director of national intelligence, has confirmed that he has “a high level of confidence” that no such work is going on now. This reflects the consensus view of 16 different U.S. intelligence agencies.

It says far more than merely that there is no evidence now for any nuclear weapons development work in Iran. It says there is actual concrete high-quality evidence that Iran is not making nuclear weapons, and that the leaders in Tehran have not even made a decision to embark on such a program.

Outgoing Defense Secretary Leon Panetta has also weighed in: “Are they [Iranians] trying to develop a nuclear weapon? No.” Mohamed ElBaradei, the Nobel Peace Prize laureate who spent more than a decade as the director of the IAEA, said he had not “seen a shred of evidence” that Iran was pursuing the bomb, “I don’t believe Iran is a clear and present danger,” he said. “All I see is the hype about the threat posed by Iran.”

In any case, if Tehran tried to “break out” and race to the bomb, this would be detected by IAEA inspectors, who check the relevant facilities roughly weekly. And all declared nuclear material in Iran, according to the IAEA, remains under the agency’s containment and surveillance.

To “break out,” either Iran would have to kick out the inspectors or the Iranians would get caught cheating. In either case, Iran would be forced to break its four-decade-long adherence to the Nuclear Non-Proliferation Treaty a momentous step that would likely prompt swift military action from the United States or Israel.

So if we are looking for real “red lines,” the obvious trip-wires should be either the expulsion of IAEA inspectors or the detection of diversion of nuclear material to non-peaceful uses – not some artificial red line drawn by a non-NPT member state.

The problem with casting the worst-case hypothetical scenarios as even vaguely realistic possibilities – as Netanyahu does with his artificially accelerated time line – is that they invite overly tough policies on Iran that could well provoke a hard-line Iranian response. This would only succeed in creating a self-fulfilling cycle of escalation.

One point often misunderstood about the Nonproliferation Treaty is that it is not illegal for a member state to have a nuclear weapons capability – or even a “nuclear option.” In fact, if a nation has a fully developed civilian nuclear sector – which the NPT encourages – it, by default, already has a fairly solid nuclear weapons capability. Just as you cannot be fined for having a red sports car that has the capability to go 120 mph, there is no legal issue with nations having a latent nuclear weapons capability.

For example, Argentina, Brazil and Japan also maintain a “nuclear option.” They, too, could break out of the NPT and make a nuclear device in a few months, if not less.

Argentina and Brazil, like Iran, also do not permit full “Additional Protocol” IAEA inspections. Not only for Iran, but for 50 other nations, the IAEA cannot prove the purely peaceful nature of their nuclear program.

There is a reason for that: Much nuclear technology is inherently dual-use. This is the why some of us in the arms-control community are thinking of a revised NPT to plug these glaring loopholes.

Unfortunately, Netanyahu’s latest claims about the time line to an Iranian bomb is not a one-off aberration. He has been making such assertions for decades. So it pays to take his views with a boulder of salt.

In 1992, Netanyahu, then a parliamentarian, said Iran was three to five years from a bomb. Then, as now, he was urging the United States to do Israel’s dirty work – and, perhaps, suffer the possible blowback – saying the alleged threat must be “uprooted by an international front headed by the U.S.”

Netanyahu’s crystal ball on Iran was cloudy 20 years ago ‑ and it seems still cloudy now.

PHOTO: Iranian President Mahmoud Ahmadinejad gestures to photographers after meeting with Indonesian counterpart Susilo Bambang Yudhoyono in Nusa Dua, Bali November 9, 2012. Ahmadinejad again denied Iran was trying to develop nuclear weapons. REUTERS/Murdani Usman

PHOTO (Insert): Iraeli Prime Minister Benjamin Netanyahu holds an illustration describing Iran’s ability to create a nuclear weapon as he addresses the 67th United Nations General Assembly at the U.N. Headquarters in New York, September 27, 2012. REUTERS/Keith Bedford