Anchored by Jake Tapper, The Lead airs at 4 p.m. ET on CNN.
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(CNN) - Iran has pledged to start eliminating some of its uranium stockpile on January 20, the White House said Sunday. That gives an official start time for the six-month interim deal with Iran, which was first announced in November.
But there are still hurdles ahead for this deal.
"Congress could certainly blow it up. If the Iranians don't comply with any of the major provisions, it could blow it up. (And) if there was a discovery a new facility, something we didn't know about," said New York Times national security correspondent David Sanger.
"But it's in the Iranians' interest right now to let that six months play out, and maybe let another six months after that play out," said Sanger.
The agreement allows for negotiation that could go on for as long as a year.
"That's important, because this interim agreement rolls back very little," said Sanger. "All it does is keep Iran from making more use of the fuel that is closest to bomb grade. But what it doesn't do is take back any of the centrifuges, the equipment that enriches uranium, and make them disassemble that. That's what the bigger disagreement is about."
In the end, said Sanger, there is only one way to measure success for this agreement.
"It's whether it increases the dash time that will be required if the Iranians ever decide to race to a bomb," said Sanger.
For more of our interview with The New York Times' David Sanger, check out the video above.