The Nimitz-class aircraft carrier USS Abraham Lincoln was deployed to the region earlier this week (Picture: US Department of Defense).
The Pentagon is sending an additional Navy ship and a Patriot air defence missile system to the Middle East, saying they are ready to defend forces and interests in the Gulf.
The USS Arlington and the Patriot will join a strike group headed by an aircraft carrier, the USS Abraham Lincoln, which has just passed through the Suez Canal.
The navy ship - which transports amphibious vehicles and aircraft - had already been scheduled to go to the Middle East but its deployment will be brought forward.
The Pentagon's announcement comes after ongoing concerns that Tehran may be planning to attack American forces or interests in the region.
An official said intelligence showed that the Iranians have loaded military equipment and missiles on to small boats controlled by Iran's Revolutionary Guard.
Tehran said the US deployments to the region are "psychological warfare" aimed at intimidating the country.
Iran's President, Hassan Rouhani said his country is facing an all-out economic and political war following the imposition of sweeping US sanctions.
He said the pressure is unprecedented in Iran's modern history - worse even than during its long, gruelling war with neighbouring Iraq in 1980.
Sending a Patriot missile defence system to the area was under discussion earlier this week and officials explained the process took a few days to get the final approval.
The Patriot is a long-range, all-weather air defence system to counter tactical ballistic missiles, cruise missiles and advanced aircraft.