The Marines have been working with Spain, Italy, the United Kingdom and other close allies to determine the suitability of the foreign ships for U.S. personnel and aircraft.

The units would be designed for limited operations and not major amphibious assaults. A ground force of about 100 to 120 Marines would be deployed along with three or four Ospreys, which fly like airplanes but can take off and land like helicopters.

The U.S. Navy has 30 amphibious ships but says it needs 38 to fulfill war fighting requirements. It won’t reach that level until 2028 because of budget constraints, according to the Navy.

Critics say the Navy has allowed its amphibious capabilities to decline.