Terms of the deal were not disclosed.

Lockheed Martin chose Alliant Techsystems over its regular contractor, Pratt & Whitney.

"The reason we got this contract is that Pratt & Whitney had a big facility out in California and it blew up last year. They lost their entire [rocket propellant] mixing facility. So Lockheed needed to secure a different source, and we won that competition," Alliant spokesman Bryce Hallowell said.

The contract dramatically expands Alliant's relationship with Lockheed Martin. Alliant previously made only the first of Lockheed's three propulsion systems for the advanced interceptor missile, called Boost Vehicle Plus. Now it will make the second- and third-stage propulsion systems as well.

The contract to make all three propulsion stages mimics one that Alliant has with Boeing's missile defense program. Boeing and Lockheed are competing for contracts in the government's Strategic Defense Initiative.

Because of the size of this new type of interceptor missile, three propulsion systems are needed. The first involves a large launch motor that takes the rocket into the atmosphere. The second stage then kicks in, taking the rocket to a higher elevation and greater speed. The third-stage motor further accelerates and begins to aim the rocket toward its target. Alliant doesn't make the final fourth stage, a guidance system responsible for the final "kill," Hallowell said.

Alliant, with $2.4 billion in annual sales and 13,600 workers, makes advanced weapons and space systems and is the largest ammunition manufacturer in the world.

Dee DePass is at ddepass@startribune.com.