The US aircraft carrier USS Abraham Lincoln passed through the Strait of Hormuz and entered the Gulf despite threats from Iran, dpa reported.
"The USS Abraham Lincoln transited through the Strait of Hormuz without incident," White House spokesman Jay Carney said Monday. "That's part of our regularly scheduled movements, undertaken in accordance with our long-standing commitments to the security and stability of the region."
The movement came as the European Union imposed new sanctions on Iranian oil, a move the White House welcomed as further pressuring Tehran on its nuclear programme.
"This process will continue to intensify, so that Iran understands fully that the pressure will not let up and the isolation will not stop until they decide to make the right choice, which is to abide by their commitments internationally and to come clean, if you will, on their nuclear aspirations," Carney said.
The carrier group was accompanied by British and French warships when it entered the Gulf Sunday, US broadcaster CNN reported.
The United States has two aircraft carriers in the Gulf - the USS Abraham Lincoln and the USS Carl Vinson - following the redeployment of the USS John Stennis to the Pacific two weeks ago.
Iran had warned the US not to send another carrier into the Gulf.
Tehran has threatened to close the Strait of Hormuz, blocking a considerable share of global oil exports, if Western sanctions are imposed on Iranian oil.
The US has responded by threatening to use military force.
On Monday, the US slapped sanctions on Iran-based Bank Tejarat, the Islamic republic's third-largest bank.