(CNN) -- There are "red lines," a "window of opportunity," the risk of a "zone of immunity," and plenty of other cryptic terms about Iran's nuclear program. What does it involve? Where is it leading? How and when should it be stopped or restrained?
Ordinary mortals can't know where those red lines lie; when the "weaponization" of Iran's nuclear material might be imminent; even what Iran's real intentions are. Experts and policy-makers differ about the time Iran would need to develop a nuclear weapon, the space for diplomacy, whether Iran wants a nuclear weapon as an instrument of deterrence or would use it pre-emptively. Or even whether it really is hell-bent on acquiring one.
James Clapper, the U.S. Director of National Intelligence, told the Senate Intelligence Committee in January that Iran was "keeping open the option to develop nuclear weapons...We do not know, however, if Iran will eventually build nuclear weapons."
Israel's Prime Minister, Benjamin Netanyahu, has no doubt. He told an audience in Washington this week: "Amazingly, some people refuse to acknowledge that Iran's goal is to develop nuclear weapons.....This duck is a nuclear duck and it's time the world started calling a duck a duck," he said.
The Islamic Republic's supreme leader, Ayatollah Ali Khamenei, repeated recently that acquiring a nuclear weapon would be "un-Islamic" (in 2005 he issued a fatwah that "the production, stockpiling and use of nuclear weapons are forbidden under Islam, and that the Islamic Republic of Iran shall never acquire these weapons.") Was he sincere? Bluffing? Or looking for a way to begin a graceful climb-down?
According to both governments, the United States and Israel are unified in their goal. "We are committed, as Israel is, to preventing Iran from acquiring a nuclear weapon," said White House spokesman Jay Carney shortly before Netayahu's visit.
But how to measure that goal? The U.S. Defense Department's Strategic Guidance, published in January, emphasized efforts "to prevent Iran's development of nuclear weapon capability."
The quandary: at what point must that "development" be thwarted before it's too late. When Iran has acquired enough low-grade uranium that could if enriched make one weapon? When there is evidence that the process of such enrichment is underway? When it has made enough highly enriched uranium for a nuclear warhead? When it has built the weapon? When it has a viable delivery system? (It already has a wide range of ballistic missiles.) How long might each of these phases take?
Even the best intelligence agencies might have problems finding out when each of those stages is imminent. After all, an accurate reading of Iraq's Weapons of Mass Destruction program seemed elusive ten years ago.
Policy-makers in Washington say Iran continues to move steadily toward the capability to build a bomb. "It has the scientific, technical and industrial capacity to eventually produce nuclear weapons, making the central issue its political will to do so," Clapper told the Senate hearing.
But in the meantime, President Obama says, there is still a window for diplomacy, and he has welcomed the scheduled resumption of multilateral talks (involving the United States, the European Union, Russia and China) with Iran.
"This notion that somehow we have a choice to make in the next week or two weeks or month or two months is not borne out by the facts," the President told a news conference Tuesday.
For the Israeli government, the timetable is more urgent, and it always has been. Netanyahu pointedly told the American Israel Public Affairs Committee Sunday: "We've waited for diplomacy to work. We've waited for sanctions to work. None of us can afford to wait much longer."
The initial enrichment process -- because it is monitored and reported by International Atomic Energy Agency - is the least difficult step in the chain to track (though that is not to suggest it is easy.) According to the latest IAEA report, published February 24th, Iran had tripled its production of 20% U-235 at the Fordow Fuel Enrichment Plant and Natanz - to some 11 kilograms a month. Uranium enriched at 20% is typically used for hospital isotopes and research reactors, but is also seen as a short-cut toward the 90% enrichment required to build nuclear weapons. Nuclear experts say Iran's supply is far greater than it would need for peaceful purposes.
Even before the February report, Olli Heinonen, a former deputy director-general at the IAEA and now at Harvard's Belfer Center for Science and International Affairs, wrote in Foreign Policy that Iran would be able to produce 15 kilograms of 20% enriched uranium a month, which he said was '"alarming."
The International Institute of Strategic Studies estimates that Iran now has a stockpile of some 110 kilograms of 20% U-235, and says that "Iran's decision to build a relatively small enrichment facility without informing the IAEA suggested that Fordow was intended to be used to quickly and securely make highly enriched uranium for nuclear weapons." The Bipartisan Policy Center in Washington says that "Iran could produce 20 kilograms of highly enriched uranium, enough for a weapon, in as little as 43 days."
Not surprisingly, the debate over Iran's intentions has taken on greater urgency as the perception has grown -- in Europe, the United States and Israel -- that Iran continues to deceive, stall and mislead international inspectors. The Director-General of the IAEA, Yukiya Amano, told CNN Wednesday: "We are asking Iran to engage with us proactively, and Iran has a case to answer."
The IAEA's February report noted that "the Agency has become increasingly concerned about the possible existence in Iran of undisclosed nuclear related activities involving military-related organizations, including activities related to the development for a nuclear payload." That followed a report in November that spoke of "experiments with conventional high explosives meant to initiate a nuclear chain reaction," at the Parchin site. IAEA inspectors have been denied access to Parchin, and diplomats say recent satellite images indicate Iran has tried to "clean up" the site ahead of allowing inspectors to visit.
Iran's obfuscation -- and its development of the facility at Fordow deep inside a mountain - has moved some to say it can't be trusted with any enrichment program. A group of 12 U.S. senators (Democrat and Republican) wrote to President Obama last month that Iran "cannot be permitted to maintain any enrichment or reprocessing activities on its territory for the foreseeable future, or continue to possess its current stockpile of both 3 percent and 20 percent low enriched uranium." Netanyahu is demanding that Iran surrender any uranium with a higher than 3.5% purity.
That would be difficult for the IAEA to enforce under international law. Iran is a signatory to the Nuclear Non-Proliferation Treaty and is entitled to develop a nuclear industry for peaceful purposes should it allow international inspections and behave transparently.
But Israel - especially - has long maintained Iran cannot be trusted to honor its obligations. U.S. diplomatic traffic published by WikiLeaks show a constant dialogue between Israel and the United States about the threat posed by Iran, with Israeli officials frequently warning of deadlines - deadlines that have come and gone.
In June 2009, then (and current) Israeli Defense Minister Ehud Barak is quoted as saying that 2010 would be a critical year. A cable quotes him as telling a visiting Congressional delegation that he "estimated a window between 6 and 18 months from now in which stopping Iran from acquiring nuclear weapons might still be viable."
After that, Barak's view was that "any military solution would result in unacceptable collateral damage," according to the cable.
Another cable, sent on November 18, 2009, reviews the 40th Joint Political Military Group meeting, an annual consultation between Israel and the U.S., also says the Israeli government had "described 2010 as a critical year."
"If the Iranians continue to protect and harden their nuclear sites, it will be more difficult to target and damage them," the cable says. And it continues: " Both sides then discussed the upcoming delivery of GBU-28 bunker-busting bombs to Israel, noting that the transfer should be handled quietly "to avoid any allegations that the USG (U.S. government) is helping Israel prepare for a strike against Iran."
A different cable on the same meeting adds the perspective of the Israeli intelligence service, Mossad.
"From Mossad's perspective, there is no reason to believe Iran will do anything but use negotiations to stall for time," the cable says, "so that by 2010-2011, Iran will have the technological capability to build a nuclear weapon -- essentially reducing the question of weaponizing to a political decision."
That was certainly not the first time Israeli officials had sounded alarm bells about the progress of Iran's nuclear program. According to a cable from 2005, then-Israeli Defense Minister Shaul Mofaz cautioned that Iran is "less than one year away (from full enrichment capability) while the head of research in military intelligence estimated that Iran would reach this point by early 2007."
Whether these predictions were inaccurately reported, or just turned out to be wrong or were designed to prod the U.S. toward more urgent action, they reflect the angst over predicting the course of Iran's nuclear program. Had they been correct, the debate today would be very different. Thereagain, they may have helped intensify and accelerate a sanctions regime that is beginning to bite.
In trying to divine Iran's -- and even Israel's intentions at this stage -- it might help to recall Winston Churchill's words about Russia's strategy as World War Two broke out. "It is a riddle wrapped in a mystery, inside an enigma," he said. "But perhaps there is a key. That key is Russian national interest."