Iran's Revolutionary Guard Corps said on Saturday it considered the likely return of US warships to the Gulf part of routine activity, backing away from previous warnings to Washington not to re-enter the area.
The statement may be seen as an effort to reduce tensions after Washington said it would respond if Iran made good on a threat to block the Strait of Hormuz.
"US warships and military forces have been in the Gulf and the Middle East region for many years and their decision in relation to the despatch of a new warship is not a new issue and it should be interpreted as part of their permanent presence," Revolutionary Guard Deputy Commander Hossein Salami told the Irna news agency.
The apparently conciliatory comments may be a response to the European Union and Washington's rejection of Iran's declaration it was close to resuming negotiations with world powers and with the Pentagon saying it did not expect any challenge to its warships.
There has been no U.S. aircraft carrier in the Gulf since the USS John C. Stennis left at the end of December at a time when the Revolutionary Guard was conducting naval manoeuvres.
On January 3, after U.S. President Barack Obama signed new sanctions aimed at stopping Iran's oil exports, Tehran told the Stennis not to return - an order interpreted by some observers in Iran and Washington as a blanket threat to any U.S. carriers.
"I recommend and emphasise to the American carrier not to return to the Gulf," Iran's army chief, Major General Ataollah Salehi, said at the time. "We are not in the habit of warning more than once."
Washington says it will return to the Gulf and Defence Secretary Leon Panetta said any move to block Hormuz would be seen as a "red line", requiring a response.
Citing operational security, the Pentagon will not say when the next carrier will return to the Gulf but officials say it is only a matter of time and they do not expect any problems.
In the coming days or weeks, the Revolutionary Guard will begin new naval exercises in the Strait of Hormuz and the Gulf. Salami told Irna these would go ahead as planned in the Iranian month of Bahman which runs from January 21 to February 19.