(CBS News) Learning the truth about Iran's nuclear program got more complicated Friday. Talks over a United Nations inspection program broke down and there is evidence that Iran has expanded its capacity to enrich uranium -- potential fuel for a nuclear weapon.
After seven hours of talks with Iranian officials, the U.N.'s top nuclear inspector, Herman Nackaerts, reported no breakthroughs.
"Discussions today were intensive but important differences remained between Iran and the Agency," he said at a press conference.
The International Atomic Energy Agency wants access to Parchin, a military site where inspectors believe Iran may have conducted preliminary tests for developing a nuclear warhead.
This new satellite photo shows buildings covered with pink tarps and fresh landscaping -- signs the site may have been cleared of potential evidence.
"There are huge suspicions about what is happening at that site," said Jon Alterman, who monitored Iran at the State Department. "Until the world sees what is happening, until inspectors are allowed to go, I think there are going to be huge concerns."
Iran also claims to have added hundreds of new centrifuges at another underground processing facility called Fordow. Inspectors say Iran continues to enrich uranium to 20 percent, just one level below bomb-grade.
Iran insists the uranium will be used for peaceful purposes, but its actions continue to be provocative.
U.S. officials say there is no evidence that Iran has decided to build a bomb. Israeli Prime Minister Benjamin Netanyahu, however, continues to signal a possible Israeli strike on Iranian nuclear facilities.
In a statement today, Netanyahu said:
"We received additional proof of the fact that Iran is continuing to make accelerated progress toward achieving nuclear weapons. "
U.S. officials have counseled restraint telling Israel there is still time for diplomatic efforts to work, but it's hard to find real optimism on any front.