Exhibit 99.1

For Immediate Release

ATK Reports FY12 Third Quarter Operating Results

ATK Tightens Full-Year Sales and Announces New EPS Guidance

ATK Announces Business Segment Realignment and Share Repurchase Program

Arlington, Va.,  Feb. 2, 2012 — ATK (NYSE: ATK) today reported operating results for the third quarter of its Fiscal Year 2012, which ended on January 1, 2012.  Fully diluted earnings per share (EPS) were $1.51, compared to $2.09 in the prior-year quarter, reflecting the impact of a $33 million ($25 million net of taxes or $0.77 per share) accrual regarding a previously disclosed lawsuit related to the manufacture of LUU flares (the LUU flares accrual) arising from events that predated the acquisition of the Thiokol Corporation in 2001. The company has reached a tentative agreement with the plaintiff and the Department of Justice (DOJ) to settle the claim.  The company expects to finalize the agreement in the fourth quarter of the fiscal year.

The prior-year quarter included a $25 million ($15 million net of taxes, or $0.45 per share) reduction in sales, profit margins and EPS associated with a commercial aerospace structures program.  Excluding the prior-year quarter sales and profit reduction, and the current quarter LUU flares accrual, third quarter EPS would be $2.28 compared to $2.54 in the prior-year quarter (see reconciliation table for details).

Third quarter orders of $701 million were in line with the company’s expectations, with year-to-date orders totaling $2.8 billion and a total backlog of $6.1 billion. Third quarter sales of $1.1 billion were down approximately one percent from the prior-year quarter.  Lower sales on

NASA human spaceflight programs and lower modernization revenues within the Armament Systems group contributed to the decrease, which was partially offset by higher sales in commercial ammunition.

Margins in the third quarter of FY12 were 9.4 percent, compared to 11.2 percent in the prior-year quarter.  Lower margins in the current quarter can be attributed to the LUU flares accrual and sales mix and higher commodity prices within the Security and Sporting group, partially offset by a reversal of the fiscal 2010-2012 long-term incentive accrual.

“Consumers purchased lower priced and lower margin ammunition products in the third quarter impacting the company’s overall margin performance.  However, ATK’s continued focus on operating efficiencies and cost reductions supported margin improvement elsewhere in the business,” said Mark DeYoung, President and CEO. “Margins in the sporting market have been at historically high levels and we expect to see some continued pressure on our sales mix and margins in this business.”

SUMMARY OF REPORTED RESULTS

The following table presents the company’s results for the third quarter of the fiscal year which ended January 1, 2012 (in thousands).

Sales:

Income before Interest, Income Taxes, and Noncontrolling Interest (Operating Profit):

2

SEGMENT RESULTS

ATK currently operates in a four business group structure: Aerospace Systems; Armament Systems; Missile Products; and Security and Sporting.

AEROSPACE SYSTEMS

Third quarter sales in the Aerospace Systems group declined by six percent to $302 million compared to $321 million in the prior-year quarter.  The decrease was primarily driven by lower sales in NASA human space flight programs, and partially offset by the absence of the $25 million sales reduction recorded in the prior-year quarter.

Earnings before interest, taxes, and noncontrolling interest (operating profit) in the third quarter increased 46 percent to $35 million, compared to $24 million in the prior-year quarter.  The increase reflects the absence of the previously mentioned profit reduction taken in the prior-year quarter, partially offset by lower sales volume in human space flight programs.

ARMAMENT SYSTEMS

Third quarter sales in the Armament Systems group decreased six percent to $404 million, compared to $431 million in the prior-year quarter.  The decrease was primarily driven by the absence of modernization funding at the Radford Army Ammunition Plant; lower modernization funding at the Lake City Army Ammunition Plant; and lower sales of medium-caliber guns, partially offset by higher energetics sales.

Operating profit in the third quarter rose 22 percent to $67 million, compared to $55 million in the prior-year quarter.  The higher operating profit primarily reflects a favorable change in the sales mix across the group and operating efficiencies in advanced weapons and energetics businesses.

MISSILE PRODUCTS

Third quarter sales in the Missile Products group increased slightly to $169 million, compared to $168 million in the prior-year quarter. The increase reflects additional sales associated with the production ramp-up of the Advanced Anti-Radiation Guided Missile (AARGM) program, partially offset by lower tactical rocket motor sales.

Operating profit in the third quarter rose by 21 percent to $24 million, compared to $19 million in the prior-year quarter, primarily reflecting the benefit of operating efficiencies.

3

SECURITY AND SPORTING

Third quarter sales in the Security and Sporting group grew by 17 percent to $243 million, compared to $209 million in the prior-year quarter.  The increase primarily reflects stronger domestic and international demand for the company’s commercial ammunition.

Operating profit in the third quarter decreased by 25 percent to $23 million compared to $30 million in the prior-year quarter.  The decrease primarily reflects a continued shift in demand toward lower-margin ammunition, and higher raw materials costs.

CORPORATE AND OTHER

In the third quarter, corporate and other expenses totaled $43 million, compared to $2 million in the prior-year quarter.  The increase primarily reflects costs associated with the LUU flares accrual, increased pension expense and higher inter-company eliminations.  The effective tax rate for the quarter was 42.0 percent compared to 30.7 percent in the prior-year quarter.  The higher rate primarily reflects the non-deductible portion of the LUU flares accrual, the absence of the benefit in the prior year from the retroactive extension of the Federal research and development (R&D) tax credit and a smaller benefit recorded this year for the Domestic Manufacturing Deduction.

REALIGNMENT

ATK announced it will operate in a three-group structure at the beginning of Fiscal Year 2013. These three operating units will be the Aerospace Group, the Defense Group, and the Sporting Group.

“The three-group structure demonstrates our ongoing commitment to competitiveness and long-term growth,” said DeYoung. “This alignment will maximize efficiency, reduce cost, support customer needs, leverage our investments, and improve overall agility within our markets.”

4

CAPITAL DEPLOYMENT

The Board of Directors approved the previously announced $.20 per share dividend for the quarter and authorized a share repurchase program of up to $200 million, which the company expects to execute over the next two years.

“ATK is determined to deliver value to our shareholders,” DeYoung said. “We will continue to execute a balanced capital deployment program, including a cash dividend, a share repurchase program, capital expenditures, debt management, and responsible growth strategies.”

The shares may be purchased from time to time in open market, block purchase, or negotiated transactions, subject to compliance with applicable laws and regulations and the company’s debt covenants, depending upon market conditions and other factors. The new repurchase authorization also allows the company to make repurchases under Rule 10b5-1 of the Securities Exchange Act of 1934.  This share repurchase program replaces the prior program authorized in 2008.

FY12 FULL-YEAR UPDATE AND INITIAL FY13 OUTLOOK

ATK now expects full-year sales of approximately $4.6 billion, compared to its previous guidance of $4.6-$4.7 billion.  Due primarily to the $33 million LUU flares accrual and lower margins within the Security and Sporting group, ATK now expects full-year EPS in a range of $7.65 - $7.75, compared to its previous range of $8.50-$9.00.

Due to the non-deductible portion of the LUU flares accrual, the company now expects a full-year tax rate of approximately 35.5 percent.  For Fiscal Year 2012, ATK continues to expect pension expense of approximately $135 million, free cash flow in a range of $225 - $250 million (despite the now-expected cash payment for the LUU flares accrual), and capital expenditures of approximately $130 million (see reconciliation table for details).

ATK’s operating results in FY13 will be impacted by the recent loss of the Radford Army Ammunition Plant, which is expected to reduce FY13 sales by approximately $170 million.  The company also expects continued pressure in its NASA and military ammunition businesses due to the constrained federal budget.  FY13 pension expense is expected to be approximately $180 million, while pension contributions are expected to be approximately $160 million compared to the $62 million the company was required to contribute in FY12.  FY13 margins in the new Sporting Group are expected to be consistent with the FY12 third quarter

5

results of the Security and Sporting group, reflecting continued demand for lower-priced and lower-margin ammunition products.

Reconciliation of Non-GAAP Financial Measures

Earnings Per Share

The Earnings Per Share (EPS) excluding the effect of the LUU flares accrual and the commercial aerospace sales and profit reduction is a non-GAAP financial measure that ATK defines as earnings per share less the impact of the LUU flares accrual and the commercial aerospace sales and profit reduction.  ATK management is presenting this measure so that a reader may compare EPS excluding these items as this measure provides investors with an important perspective on the operating results of the Company.  ATK management uses this measurement internally to assess business performance and ATK’s definition may differ from that used by other companies.

6

Total ATK for the Quarter Ending

January 1, 2012:

January 2, 2011:

7

Free Cash Flow

Free cash flow is defined as cash provided by (used for) operating activities less capital expenditures.  ATK management believes free cash flow provides investors with an important perspective on the cash available for debt repayment, cash dividends, share repurchases, and acquisitions after making the capital investments required to support ongoing business operations.  ATK management uses free cash flow internally to assess both business performance and overall liquidity.

ATK is an aerospace, defense, and commercial products company with operations in 22 states, Puerto Rico, and internationally, and revenues of approximately $4.8 billion.  News and information can be found on the Internet at www.atk.com.

Certain information discussed in this press release constitutes forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995.  Although ATK believes that the expectations reflected in such forward-looking statements are based on reasonable assumptions, it can give no assurance that its expectations will be achieved. Forward-looking information is subject to certain risks, trends, and uncertainties that could cause actual results to differ materially from those projected. Among these factors are: assumptions related to the profitability of current commercial aerospace structures programs; uncertainties related to the development of NASA’s new Space Launch System; demand for commercial and military ammunition; changes in governmental spending, budgetary policies and product sourcing strategies; the company’s competitive environment; risks inherent in the development and manufacture of advanced technology; risks associated with the diversification into new markets; assumptions regarding the company’s long-term growth strategy; assumptions regarding the growth opportunities in international and commercial markets; increases in commodity costs, energy prices, and production costs; the terms and timing of awards and contracts; program

8

performance; program terminations; changes in cost estimates related to relocation of facilities; the outcome of contingencies, including litigation and environmental remediation; actual pension asset returns and assumptions regarding future returns, discount rates and service costs; capital market volatility and corresponding assumptions related to the company’s shares outstanding; the availability of capital market financing; changes to accounting standards; changes in tax rules or pronouncements; economic conditions; and the company’s capital deployment strategy, including debt repayment, dividend payments, share repurchases, pension funding, mergers and acquisitions — including the related costs and any integration thereof. ATK undertakes no obligation to update any forward-looking statements. For further information on factors that could impact ATK, and statements contained herein, please refer to ATK’s most recent Annual Report on Form 10-K and any subsequent quarterly reports on Form 10-Q and current reports on Form 8-K filed with the U.S. Securities and Exchange Commission.

#    #    #

9

ALLIANT TECHSYSTEMS INC.

CONDENSED CONSOLIDATED INCOME STATEMENTS

(preliminary and unaudited)

ALLIANT TECHSYSTEMS INC.

CONDENSED CONSOLIDATED BALANCE SHEETS

(preliminary and unaudited)

ALLIANT TECHSYSTEMS INC.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(preliminary and unaudited)