The USS Arlington, which transports marines, amphibious vehicles, conventional landing craft and rotary aircraft, and the Patriot air defense system will join the USS Abraham Lincoln Carrier Strike Group and a B-52 bomber task force headed toward the Gulf after intelligence reports suggested Iran was planning some sort of attack in the region.

The deployment is "in response to indications of heightened Iranian readiness to conduct offensive operations against US forces and our interests," the Pentagon said in a statement.

"The Department of Defense continues to closely monitor the activities of the Iranian regime, their military and proxies," it said.

"The United States does not seek conflict with Iran, but we are postured and ready to defend US forces and interests in the region."