The US Navy’s Portsmouth Naval Shipyard has held a ground-breaking ceremony to mark the start of work on the $1.7bn new multi-mission dry dock project.

The multi-mission dry dock will provide extended capacity to accommodate three Los Angeles or Virginia-class attack submarines for repair, maintenance, and upgradation at the same time.

The latest seven-year construction project will upgrade the dry dock, enabling Portsmouth naval yard to meet the US Navy’s requirements in the coming years.

The project is part of the Shipyard Infrastructure Optimization Program (SIOP).

SIOP is a joint effort between aval Sea Systems Command (NAVSEA), Naval Facilities Engineering Systems Command (NAVFAC), and Navy Installations Command (NIC) to modernise to modernise four public naval shipyards to support the combat readiness of the navy.

Repairing and modernising dry docks, restoring shipyard facilities, and replacing aging and deteriorating capital equipment are some of the works included in the SIOP programme.

US Navy Secretary Carlos Del Toro said: “This is a significant investment by the American people, and because of this investment, they can sleep more securely, because they’ll know our attack fleet can rely on quick and available maintenance and repair.

“Today’s ground-breaking cements the future of Portsmouth Naval Shipyard and the future of our submarine force.”

According to the US Navy, the Dry Dock 1 area was first built during the World War II for submarine production.

In June 2018, NAVSEA established SIOP Program Office, PMS-555, to coordinate the plan to recapitalise the shipyards.

In April 2019, NAVSEA started work on the $21bn SIOP project to modernise four public naval shipyards.

The four US Navy public shipyards to receive the upgrades are Norfolk Naval Shipyard in Virginia, Portsmouth Naval Shipyard in Maine, Puget Sound Naval Shipyard and Intermediate Maintenance Facility in Washington, and Pearl Harbor Naval Shipyard and Intermediate Maintenance Facility in Hawaii.