"I don't think we'll have two carriers there for a protracted period of time. So I don't see it as an escalation.

 

"I think it could be seen, though, as a reminder."

 

He gave no further detail of the operation.

 

'No military strike'

 

Geoff Morrell, a Pentagon spokesman, said that the USS Abraham Lincoln arrived in the Gulf on Tuesday to replace the USS Harry Truman, on current duty, which is due to leave the area in a few days.

 

When asked here whether the Pentagon was preparing for military strikes against Iran, Gates said: "No."

 

The US and Iran have been at odds over Iran's supposed nuclear arms programme. Tehran says it is attempting to create nuclear energy, rather than weapons.

 

The US has also accused Iran of providing Shia fighters in Iraq with training and arms to be used against US-led forces.

 

Tensions have also risen at sea in the Gulf region with confrontations between US ships and small boats, some labelled Iranian crafts by the US.

 

A cargo ship hired by the US military fired warning shots at two unidentified ships last week as they approached the US vessel.

 

The US said that the two ships had not taken heed of radio communications or a warning flare.