VICTORIA, British Columbia — Raytheon Canada Limited has received a contact from the Canadian government worth CN$704 million (U.S. $570 million) to maintain and upgrade the Phalanx Close-In Weapon Systems operated by the Royal Canadian Navy.

The contract covers 21 such systems.

The rapid-fire, radar-guided gun system was described by Canadian Defence Minister Harjit Sajjan, in announcing the contract, as the most effective naval self-defense system available against close-in threats such as missiles, small ships and aircraft.

“It is the last line of defense for the backbone of the Royal Canadian Navy — the Halifax-class frigate,” he said.

The CIWS in-service support contract will be valid until late 2037.

The contract will update all 21 Phalanx CIWS and provide engineering services, project management, support and disposal services, as well as the procurement of spares and test equipment, according to Canada’s Department of National Defence.

A number of the upgrades will center on improvements to the gun’s radar system, a Department of National Defence official said.

The previous contract to maintain the systems was also with Raytheon Canada and lasted 10 years. The value of that was deal was CN$189 million.

The increase in value represents the planned improvements with the radar, the need for more maintenance because of the older nature of the system and the longer period for the maintenance, the department official said.

Each of the 12 Royal Canadian Navy Halifax-class frigates carry a Phalanx CIWS. Others are used for training.

The service also plans to install the systems on the new joint support ships. Those supply vessels are to be built at Seaspan Shipyards in Vancouver and are expected to be available after 2021.