As if tensions between the United States and Iran weren't high enough, here's PBS NewsHour anchor Margaret Warner (1/9/12):
The Iranian government insists that its nuclear activities are for peaceful energy purposes only, an assertion disputed by the U.S. and its allies. On CBS yesterday, Secretary of Defense Leon Panetta repeated international demands that Iran stop enriching uranium.
SECRETARY OF DEFENSE LEON PANETTA: But we know that they're trying to develop a nuclear capability, and that's what concerns us. And our red line to Iran is, do not develop a nuclear weapon. That's a red line for us. They need to know that, if they take that step, that they're going to get stopped.
The way that's presented you'd think that the United States has evidence that Iran is pursuing a weapon. Leon Panetta's soundbite is from his appearance on Face The Nation on Sunday. But the NewsHour removed one key phrase; right before Panetta says, "But we know," he said this:
Are they trying to develop a nuclear weapon? No.
So Panetta's statement–that Iran is not building a nuclear weapon–is being used to argue that the United States disputes Iran's long-standing contention that it not building a nuclear weapon.