HUNTSVILLE, Alabama (Reuters) -L3Harris Technologies' business unit Aerojet Rocketdyne has doubled its monthly production of motors for GMLRS rockets that are heavily used in Ukraine, a company executive said on Tuesday, as global demand surges to supply Kyiv and to rebuild shrinking U.S. stockpiles.

Demand for rocket motors is soaring worldwide because of wars in Ukraine and the Middle East. Other militaries are also realizing that future conflicts will likely require many more rockets and missiles - as a part of a new warfighting doctrine dubbed "affordable mass" to describe the sheer volume of firepower involved.

This is good news for L3Harris. In December 2022 the U.S. defense contractor offered to purchase Aerojet, which produces about half of all the rocket motors propelling U.S. military missiles, rockets and other projectiles. But at that time no one knew how long the Ukraine war would last and the Pentagon had signed few contracts to restock its shelves.

Guided Multiple Launch Rocket System rockets, also known as GMLRS, travel about 45 miles (72 km). Their widespread use and success in Ukraine has driven demand from new customers.

"GMLRS was a program that we have kind of unbounded demand for. In the most recent quarter, we've doubled the production that we averaged per month from 2023," said Ross Niebergall, president of Aerojet Rocketdyne.

Since closing on the deal to buy Aerojet, Niebergall said L3Harris has increased capital spending for the rocket motor unit by 84%, while also flooding as many as 75 suppliers with over $25 million to help increase productivity.

Aerojet did not provide GMLRS motor production figures. But Lockheed Martin, the main contractor for GMLRS, was making about 4,600 per year before ramping up production in 2022. Lockheed's GMLRS production is scheduled to rise from 10,000 deliveries in 2024 to 14,000 deliveries in 2025.

The GMLRS production line also uses motors from Northrop Grumman.

The strong demand has spurred new entrants into the U.S. rocket motor manufacturing business, but they do not have mass production capabilities.

Aerojet's facilities around Huntsville, Alabama, have been built out with investments in large carbon-fiber winding devices to make advanced cases, new more automated presses for nozzles and fittings, and better quality control technology under L3Harris' ownership since the deal closed just over a year ago.

The newly fitted-out building produces the critical casings for the most in-demand solid fuel rocket motors, like Javelin antitank weapons and GMLRS rockets as well as much larger rocket motors.