ATK Successfully Completes Second Static Test Firing of Solid Rocket Motor for Boeing Delta IV Launch Vehicle Family

Minneapolis, April 27, 2000 – ATK (Alliant Techsystems, NYSE: ATK) said Alliant Aerospace Propulsion
Company, Magna, Utah, today successfully completed the second of three static test firings to qualify a new solid
rocket motor for The Boeing Company’s Delta IV Medium-plus family of launch vehicles.

The Delta IV vehicles are the latest derivative of the Delta family of rockets that has been lifting satellites into orbit
since 1960. The new graphite epoxy motor, known as GEM-60, is designed to provide a lift capacity ranging
between 12,890 and 14,475 pounds to geosynchronous transfer orbit (GTO) for the Delta IV Medium-plus family of
vehicles.

Jeff Foote, president, Alliant Aerospace Propulsion Company, said the new GEM-60 motor performed flawlessly
during the second static firing, which tested the motor at cold temperature and employed the thrust vector control
system.

“The results achieved in the first two test firings indicate that we are squarely on track to qualify this important
new solid rocket booster,” said Foote. “The GEM-60 development program has proceeded smoothly and on
schedule from the very beginning, thanks to a strong partnership between Boeing and Alliant Aerospace
Propulsion Company. We are looking forward to the final static test firing next month and the culmination of a
great team effort.”

The Boeing Delta IV family of launch vehicles is designed to meet the growing needs of satellite builders and
users around the globe for reliable and affordable access to space.

Alliant Aerospace Propulsion Company is part of ATK’s Aerospace group, which comprises the company’s space
and strategic propulsion and Utah- and Mississippi-based composite structures operations. The group employs
approximately 1,700 people in California, Florida, Mississippi, New York, and Utah. Sales in fiscal year 1999 were
$395 million. The GEM-60 motors are manufactured at the group’s Utah Composites Center in Clearfield, Utah,
and Utah Propulsion Center in Magna, Utah.

ATK is a $1.1 billion aerospace and defense company with leading market positions in munitions, solid
propulsion, composite structures, and precision electronic fuzes. The company, which is headquartered in
Hopkins, Minn., employs approximately 6,400 people and has three business segments: Conventional Munitions,
Aerospace, and Defense Systems. ATK news and information can be found on the Internet at www.atk.com.