"We do not believe they have the capability to enrich to the degree to which they now say they are enriching," Press Secretary Robert Gibbs said.
Until now Iran's centrifuges have been spinning out uranium at 3 per cent enrichment, reports CBS News chief national security correspondent David Martin. Today Iran claimed it has begun enriching to 20 per cent. That would still leave it well short of the 80 per cent needed for weapons-grade uranium, but former weapons inspector David Albright says getting to 20 per cent is the hard part.
"Once they're at 20, they've done the real heavy lifting of getting to weapons grade uranium," Albright said.
Iran claims it needs the higher enrichment levels to fuel a nuclear research reactor but those same levels would bring Iran one giant step closer to being able to build a bomb.
"It just develops a stock of material it can use to more quickly break out and build one - a nuclear weapon," Albright said.
But Albright says Iran is experiencing technical problems with its centrifuges.
"They're breaking," he said. "They have problems running uranium into them and getting the right amount of, of the level of enrichment."
That's buying the U.S. time to come up with economic sanctions that might convince Iran's leaders their nuclear program is not worth the price.
And according to the White House, more countries are willing to sign up for sanctions.
"The actions of Iran have led the world to be more unified than at virtually any other point in the past many years," Gibbs said.
But so far technical difficulties seem to be doing more than sanctions to at least slow down Iran's nuclear program.