A US aircraft carrier sailed into the Persian Gulf on Friday amid Iranian threats to close the Strait of Hormuz, the only sea passage from the Gulf to the open ocean and strategic waterway linking the Middle East crude producers to crucial world markets.

Some 30 Iranian Revolutionary Guard vessels fired rockets in the waters patrolled by a US aircraft carrier strike group led by USS John C. Stennis on Friday, AP reported. At one point, one small ship launched what looked like a "commercial-grade" drone to film the US vessels, the media outlet wrote, adding that journalists on the Stennis were also filming the Iranian boats.

There were no immediate reports of the Stennis' arrival in the Persian Gulf in Iranian media. The Stennis-led group was deployed on 8 December, thus ending the longest period in two decades that a carrier group was absent from the region. The vessels took part in a joint naval exercise with the Essex Amphibious Ready Group (ARG) on 12 December in the Arabian Sea.

Earlier on Friday, Mehr News Agency quoted Brigadier General Mohammad Pakpour, commander of IRG ground forces, as saying that the final stage of the "Great Prophet 12" drills would kick off on Saturday and include "rapid reaction units, airborne units, demolition and combat units, mid-range missiles and the third marine division".

Tensions between the two countries have further escalated since US President Donald Trump announced the decision to withdraw from the 2015 Joint Comprehensive Plan of Action (JCPOA), also known as the Iran nuclear deal, which saw anti-Iran sanctions lifted in exchange for Tehran maintaining the peaceful nature of its nuclear programme. 

Trump also decided to reinstate all sanctions and introduce a new set of restrictions on the Islamic Republic's energy, shipping, financial and other sectors, with a stated goal to cut Tehran's oil exports to zero.

Iran's military leadership, in turn, has repeatedly warned against any provocations, threatening to close off the Strait of Hormuz, the narrow mouth of the Persian Gulf and the only outlet through which all ship traffic passes.