Actually, the headline undersells this a bit. By saying 'key nuclear material', they act like they are just missing one of several materials. But the 'key nuclear material' that they are missing is the essential stuff that goes BOOM to make a nuclear bomb.
Kinda like calling flour a 'key material' for a cake. Or maybe calling 'eggs' a 'key material for 'scrambled eggs'.
This is the most important thing to watch in the discussions about Iran and nuclear weapons. Do they have the highly enriched uranium that they need for a bomb? Don't let the corporate media confuse you on this. There are two dramatically different levels of enrichment for a nuclear power plant and a nuclear weapon. A nuclear power plant require enrichment to around 3% U-235. A nuclear weapon requires enrichment to somewhere around 95% U-235. The two aren't even close. Doing one doesn't mean that they've done the other. Doing the 3% enrichment (referred to as 'low-level' in this AP piece) doesn't even mean that they are capable of doing 95% enrichment.
Inspectors should be able to tell if a facility has been used to enrich beyond 3%. As just one example, they could test trace residues left on equipment or in pipes and see if there is more U-235 than they would expect from low-level enrichment. I won't say that's completely certain, but it seems like a massive amount of work would need to be done to scrub an industrial facility to hide that sort of high-level enrichment.
The key point is that at no time has the IAEA ever said that they've found more than 3% enrichment in Iran. And here you have the leaders of US intelligence saying they have no evidence that Iran has gone beyond 3% enrichment.
This is the key fact to watch. Ignore a lot of the other BS that the killers throw around to justify another war. If you don't ever see PROOF, rock-solid proof, that Iran has gone to bomb-grade, 95% or so enrichment, then you should assume that its just the lying killers who used phony fears of a non-existent nuclear weapon to start that war trying to do it again.
U.S. National Intelligence Director Dennis Blair and Defense Intelligence Agency Director Lt. Gen. Michael Maples said Tuesday that Iran has only low-enriched uranium — which would need to be refined into highly enriched uranium before it can fuel a warhead. Neither officials said there were indications that refining has occurred.
See Also: Muslim Weapons of Mass Destruction by Eric Margolis
UN inspectors report Iran has produced 1,010 kg of 2–3% enriched uranium (LEU). Iran insists it is for energy generation. Theoretically that is enough for one atomic bomb.
But to make a nuclear weapon, U-235 must be enriched to over 90% in an elaborate, costly process. Iran is not doing so, say UN inspectors, though they have raised certain technical questions about Iran’s nuclear process. Some believe Iran may go up to "breakout position," that is, having the components to assemble a weapon on fairly short notice.
Mr. Margolis is mostly very accurate in this piece. But I strongly disagree when he says 1000 kg of 2.5% enriched Uranium is 'theoretically enough for one atomic bomb.' You can have all the 2.5% enriched uranium you want and it will NEVER be enough for a bomb. Because to have a bomb you need it enriched to somewhere in the 90% range. Since he goes on to say something similar in the next sentence, I'm hoping maybe bad editing got to Mr. Margolis on that sentence.