The United States vowed Tuesday to keep American warships deployed in the Gulf region, despite Iran issuing warnings over the Strait of Hormuz.
"The deployment of US military assets in the Persian Gulf region will continue as it has for decades," Pentagon press secretary George Little said in a statement.
The movement of US aircraft carriers and accompanying ships in the Gulf and through the strategic Strait of Hormuz were part of longstanding security commitments, supported US military operations in the region and were in compliance with the laws of the sea, he said.
"Our transits of the Strait of Hormuz continue to be in compliance with international law, which guarantees our vessels the right of transit passage," he said.
"We are committed to protecting maritime freedoms that are the basis for global prosperity; this is one of the main reasons our military forces operate in the region," he said, without referring directly to Iran.
The Pentagon statement came after Tehran's military on Tuesday warned that one of the US Navy's biggest aircraft carriers -- the USS John C. Stennis -- not to return to the Gulf, amid escalating tensions over Tehran's nuclear ambitions.
"We advise and insist that this warship not return to its former base in the Persian Gulf," said Brigadier General Ataollah Salehi, Iran's armed forces chief.
"We don't have the intention of repeating our warning, and we warn only once," he was quoted as saying by the armed forces' official website.
The Stennis, a nuclear-power "supercarrier" that transports up to 90 warplanes and helicopters -- including F/A-18 Hornet fighter jets -- passed through the Strait of Hormuz last Tuesday without incident, according to the US Navy.
The carrier is now in the Arabian Sea where it is providing air power for US-led troops in Afghanistan but defense officials have not said when it might be heading back through the Strait of Hormuz.
Although such missions can last weeks or months, the carrier has been at sea for nearly seven months and it was possible another carrier group might relieve the Stennis.
Iran, which held war games and test-fired missiles near the Strait in recent days, has issued threats and warnings after Western governments backed plans for more punitive sanctions over Tehran's nuclear program.
Iran said it was prepared to close the Strait of Hormuz, a crucial route for global oil shipments, if the West went ahead with the sanctions designed to pile pressure on Tehran over its uranium enrichment work.
At the weekend, US President Barack Obama signed into law new sanctions targeting Iran's central bank, which processes most of the Islamic republic's oil export sales.
The European Union, which is mulling an embargo on Iranian oil, is expected to announce further sanctions of its own at the end of January.