Its departure came as a new round of indirect talks between the United States and Iran on the latter's nuclear programme, mediated by Oman's foreign minister, opened in Geneva Thursday morning.

The vessel has been at the US Naval Support Activity Souda Bay base in Crete since Monday. The US embassy in Athens has declined to comment on the carrier's presence, forwarding questions to the Pentagon in Washington.

President Donald Trump ordered strikes on Iran last year. He has repeatedly threatened Tehran with fresh military action if it does not cut a new deal on its contentious nuclear programme, which the West fears is aimed at building an atomic weapon.

Washington has more than a dozen warships in the Middle East: one aircraft carrier -- the USS Abraham Lincoln -- nine destroyers and three other combat ships.

It is rare for there to be two US aircraft carriers, which carry dozens of warplanes and are crewed by thousands of sailors, in the Middle East.