Tucson-based Raytheon Missile Systems is restarting the production line for its Standard Missile-2 naval missile to fill a $652 million production order from four international customers.

Raytheon said the Netherlands, Japan, Australia and South Korea aligned their requirements and pooled resources to make a “bundle” SM-2 purchase through the Pentagon’s foreign military sales program.

With a range of more than 100 miles, the SM-2 is primarily used by U.S. and allied navies for fleet air-defense and ship self-defense.

Missile Systems President Taylor Lawrence said in a statement that the SM-2 remains a “backbone” of the allies’ fleet defense, but there haven’t been enough international orders to keep the production line going.

The new contract, worth $652 million over time with all options exercised, will have Raytheon producing SM-2s well beyond 2035, he said.

New deliveries are scheduled to begin in 2020 and will include more than 280 SM-2 Block IIIA and IIIB missiles, the latest versions. More than half of the missiles will go to Japan, according to a Defense Department contract notice.

Raytheon and the U.S. Navy are using the restart as an opportunity to modernize production and testing processes in the company’s SM-2 factory, the company said.

According to the Pentagon, about 60 percent of the work will be performed in Tucson, where Raytheon is the area’s largest private employer with about 10,000 workers.

Besides the four nations involved in the new production contract, SM-2 international customers include Canada, Germany, Spain and Taiwan, Raytheon said.

Contact senior reporter David Wichner at dwichner@tucson.com or 573-4181. On Twitter: @dwichner