Iran's UN Fact Sheet: Weapons Track Not Confirmed Nine years ago, the United States invaded Iraq after telling the world that Saddam Hussein had covert weapons programs that could build nuclear arms. In the end, nothing was found. Today, acting on similar fears, Israel is threatening to attack Iran. While much is known about Iran's nuclear activities from U.N. inspection visits, significant questions remain uncertain, fueling fears of worst-case scenarios and calls for new Mideast military action. This much shapes the anxieties: In just one decade, Iran's modest nuclear program has expanded into a mature operation that some experts say has the capability to produce a warhead in less than a year. And this much is verified: Iran has the equipment and raw materials to produce the fissile core of a nuclear weapon, as does any country that can produce its own reactor fuel. But there is no evidence that the Islamic Republic has taken steps in that direction. Finally, this much is suspected: The U.N. nuclear watchdog says there are credible indications Iran is researching the intricate technology needed to turn a core into an actual bomb. Tehran denies it, and there's not conclusive proof or any sign it has actually succeeded, but the research alone if confirmed would be seen as clear proof of Iran's intentions. Reports by the U.N. nuclear agency, the only international organization given firsthand views of Iranian nuclear sites, contain a mix of confirmed data and a variety of theories built on outside intelligence. An Associated Press analysis of the published data by the International Atomic Energy Agency and interviews with officials probes the critical questions on Iran's nuclear ambitions: What can it do and what can't it do now? Iran's ability to turn uranium into nuclear fuel is at the heart of the confrontation with the West and its allies, which worry that Tehran could push ahead with higher uranium enrichment levels needed for an atomic weapon. Iran says its only aim is to fuel reactors for peaceful energy production and medical research. Iran is currently running nearly 9,000 centrifuges enriching uranium to produce nuclear fuel, a jump from 8,000 a year ago, according to reports and interviews with officials at the U.N.'s International Atomic Energy Agency. From its main enrichment site, Iran has stockpiled at least 5.5 tons of uranium enriched to 3.5 percent levels, the IAEA says. That is a sufficient level to power reactors, while uranium enriched to at least 90 percent is needed to produce the material for a bomb. Iran also has churned out 110 kilograms - nearly 250 pounds - of 20 percent enriched uranium, which it says is needed to fuel a medical research reactor in Tehran. In the past three months, Iran has nearly tripled the number of devices producing 20 percent uranium - nearly 700 centrifuges strung together in four separate series. They can churn it out a rate of about 14 kilograms, or nearly 30 pounds, a month, the IAEA says. Finally, Iran is building a "heavy water" research reactor, which issues high-pressure fluid as a coolant and can be used with natural uranium as a fuel instead of enriched states of the mineral. The IAEA estimates it could be complete in two to three years and, once in operation, will produce plutonium, another possible pathway to nuclear arms.