The United States is raising the stakes in its bid to halt Iran's nuclear program, putting the issue on a "pressure track," top US general David Petraeus said Sunday.
The US and other world powers are drumming up support for a fourth round of UN sanctions against Iran for its refusal to comply with repeated ultimatums to suspend uranium enrichment and agree to a UN-backed nuclear fuel deal.
President Barack Obama had talked about a dual-track approach to dealing with Iran's suspect nuclear activities, involving efforts to engage Iranian leaders backed up by the threat of further sanctions.
"I think that no one at the end of this time can say that the United States and the rest of the world have not given Iran every opportunity to resolve the issues diplomatically," Petraeus, the head of US Central Command, said.
"That puts us in a solid foundation now to go on what is termed the pressure track. That's the course on which we are embarked now," he told NBC television's "Meet the Press" program.
Petraeus said the administration intends to "send the kind of signal to Iran about the very serious concerns that the countries in the region and, indeed, the entire world have... about Iran's activities in the nuclear program."
'New national intelligence estimate being developed'
Concerns on Iran rose last week when the International Atomic Energy Agency, the UN's nuclear watchdog, said it suspected that Tehran might already be trying to develop a nuclear warhead.
A US intelligence report in 2007 said Iran halted such research in 2003, but the latest IAEA report gives credence to the belief held by some Western countries that the program continued.
Petraeus suggested that Iran's recent actions were leading US intelligence agencies to update their estimations.
"There is no question that some of the activities have advanced during that time. There is also a new national intelligence estimate being developed by our intelligence community in the United States," he said.
The IAEA also confirmed on Thursday that Tehran had begun enriching uranium to higher levels, theoretically bringing it closer to the levels needed for an atomic bomb.
Iran has previously reached uranium enrichment levels of no more than five percent at its facility at Natanz, in defiance of UN orders for it to cease and despite three rounds of UN sanctions.
Earlier this month, Iran announced it would begin enriching uranium to 20 percent, ostensibly to make the fuel for a research reactor that makes medical radioisotopes.
Iranian officials have dismissed the IAEA report and the country's all-powerful supreme leader Ayatollah Ali Khamenei denied on Friday that Tehran was seeking atomic weapons.
Last year the IAEA proposed sending Iranian low-enriched uranium (LEU) abroad for further enrichment, denying Tehran refining capacity world powers fear could be used to help build an atomic bomb.
The offer would have seen the uranium returned to Iran in a high-grade form for use in a medical research reactor, but Tehran rejected the plan.
Iranian President Mahmoud Ahmadinejad insisted that the exchange had to be "simultaneous," an Iranian stance that has led to a deadlock over the deal.