"I think it's important to ratchet up the pressure as much as we can on Iran ... internationally, financially, diplomatically ... without taking the combat option off the table."
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His remarks echo those of Robert Gates, the US defence secretary, who said this week that he favoured avoiding the military option against Iran while warning that Tehran was "hell-bent" on acquiring nuclear weapons.

On Wednesday, Mahmoud Ahmadinejad, the Iranian president, said his country was ready to discuss its nuclear programme with any country, but would not yield to international pressure to halt the project.

The US government last month denied it was preparing to take military action against Iran before George Bush's term as president expires early next year.

Iran differences
Speculation had increased since Admiral William Fallon, the US military commander in charge of Middle East operations, resigned over reported differences with Bush over Iran, differences the White House denied.
Fallon was reportedly opposed to the US using force against Iran over its nuclear programme.

US military power

The US military has troops in over 800 locations around the world and in 70 per cent of countries


1.6 million troops available for active duty in the US and abroad


546,000 troops in total deployed around the globe


Biggest single deployment is in Iraq with 161,000 


In Europe, more than 57,000 are in Germany and more than 9,800 in the UK


Ecuador hosts the only US military base in Latin America


Sub-Saharan Africa becoming a greater focus for deployment with more than 2,400 troops stationed across region


Source: Pentagon

Gates announced this week that he had nominated General David Petraeus, the highest US commander in Iraq, to take over as head of US Central Command from Fallon.

On Iraq, Mullen called on Iraqi leaders to "step forward" and take advantage of the reported decline in violence there.

"There have been improvements particularly tied to the surge and leaders of Iraq really have to step forward and take advantage of that," said Mullen, the highest ranking commander in the US military.
"If they do that then ... I think there is a potential for a positive outcome."
He refused, however, to commit to a date for a significant withdrawal of US forces from Iraq.
"What we do is going to be based on conditions on the ground," he said.
The US military chief also said the US did not have enough troops in Afghanistan to comprehensively defeat the Taliban.
Making clear that he thought the Taliban had "not won on the battlefield", he said it was "resurgent" and "we don't have enough troops to conduct a counter-insurgency campaign".
You can watch the full interview with Admiral Michael Mullen on Friday at 1630 GMT on Talk to Al-Jazeera.