Exhibit 99.1

For Immediate Release

ATK Reports First-Quarter Operating Results

ATK Receives Strong Orders Volume in the First Quarter

ATK Reduces Debt to Strengthen Balance Sheet

ATK Increases Full-Year FY13 Sales, EPS and Free Cash Flow Guidance

Arlington, Va., Aug. 9, 2012 — ATK (NYSE: ATK) today reported operating results for the first quarter of its Fiscal Year 2013, which ended on July 1, 2012.  Orders were $1.1 billion, representing a book-to-bill ratio of approximately 1:1, driven by strong orders in the Defense and Sporting Groups. First quarter sales were flat year over year at $1.1 billion, reflecting increased sales in the Sporting and Defense Groups, partially offset by a decrease in the Aerospace Group, consistent with ATK’s expectations. Margins in the first quarter were also flat with the prior-year quarter at 12.1 percent. Margins were impacted by higher profit rates, which included a gain on the sale of residual assets as ATK completed contracts in the Defense Group, offset by lower margins in the Sporting and Aerospace Groups and an increase in pension expense. Net income for the quarter was down 1 percent to $71, million compared to $72 million in the prior-year quarter, due to a higher tax rate, partially offset by lower interest expense. Fully-diluted earnings per share were $2.16, compared to $2.13 in the prior-year period.

“ATK recorded a solid quarter with strong program execution and orders flow and increased ammunition sales volume,” said Mark DeYoung, President and Chief Executive Officer.  “As we look forward across the ATK portfolio, we remain focused on maintaining a sound backlog and delivering quality products that exceed customer expectations. We continue to look for opportunities

for growth, margin improvement and cost reductions necessary to succeed in a challenging marketplace.”

SUMMARY OF REPORTED RESULTS

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

Sales:

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

SEGMENT RESULTS

ATK operates in a three business group structure: the Aerospace Group, the Defense Group and the Sporting Group.

AEROSPACE GROUP

First quarter sales fell 17 percent to $295 million, compared to $354 million in the prior-year period. The decrease primarily reflects lower NASA revenue in the space systems operations division and lower revenue in commercial aerospace structures.

Operating profit in the quarter decreased 18 percent to $35 million, compared to $43 million in the prior-year quarter. The decrease reflects lower sales as noted above and the absence of a gain from the sale of a non-essential parcel of land to the State of Utah, recorded in the prior year. The decrease was partially offset by increased profit within the space structures and components division.

DEFENSE GROUP

Sales in the first quarter increased by 5 percent to $514 million compared to $492 million in the prior-year quarter. The increase was driven primarily by higher volume and updated sales and profit rates as ATK completed contracts at the Radford Army Ammunition Plant (RFAAP).

Operating profit for the quarter increased 48 percent to $91 million, compared to $62 million in the prior-year quarter, resulting from higher sales and updated profit rates, primarily driven by a gain on the sale of residual assets and improved performance as the Company completed contracts at the RFAAP.

SPORTING GROUP

First quarter sales increased by 19 percent to $273 million, compared to $229 million in the prior-year quarter. The increase in sales was primarily driven by higher volume in both the ammunition and accessories divisions.

Operating profit in the first quarter decreased by 29 percent to $21 million, compared to $29 million in the prior-year quarter, primarily reflecting a continued shift in demand toward lower-margin ammunition and costs associated with the closeout of certain facilities, partially offset by higher sales volume.

CORPORATE AND OTHER

In the first quarter, corporate and other expenses totaled $16 million, compared to expenses of $3 million in the prior-year quarter, primarily reflecting increased pension expense. The tax rate for the quarter was 36.1 percent compared to 31.2 percent in the prior-year quarter, reflecting the absence of a benefit from a state tax law change in the prior year and the absence of the Federal Research and Development (R&D) tax credit, which expired on December 31, 2011.  Interest expense was $19.7 million compared to $26.3 million in the prior-year quarter, which reflects reduced rates and debt levels year over year.  Free cash flow use was $320 million in the first quarter, up $127 million from the prior-year quarter (see reconciliation table for details). The higher use reflects pension contributions of approximately $140 million, compared to $62 million in the prior-year quarter, and a payment of approximately $25 million related to a legal settlement accrued in the prior year. During the quarter, the company repurchased $25 million of common stock.

In early August, ATK exercised its right to call its $400 million, 6.75% notes maturing in 2016 (the “6.75% Notes”). Calling those notes will result in debt extinguishment charges of approximately $12 million, to be reflected in ATK’s results for the second quarter ending September 30, 2012. In conjunction with the above, it is ATK’s intention to partially finance the call by

increasing its Senior Secured Term Loan A borrowings by $200 million. The balance of the redemption will be paid from available cash and/or ATK’s existing credit facility. This action will further improve ATK’s balance sheet and increase earnings per share by reducing interest expense.

OUTLOOK

Based on first quarter results and a lower-than-expected full-year tax rate, ATK is raising its full-year FY13 sales guidance to $4.05 to $4.15 billion, up from previous guidance of $4.0 to $4.1 billion; full-year FY13 EPS guidance to $7.00 to $7.30, up from previous guidance of $6.25 to $6.55; and full-year FY13 free cash flow guidance in the range of $140 to $165 million, up from $125 to $150 million (see reconciliation table for details).

ATK expects FY13 pension expense of approximately $168 million. The effective tax rate for the year is now expected to be approximately 32 percent, down from previous expectations of approximately 34.5 percent. The lower tax rate, which anticipates the retroactive extension of the Federal R&D tax credit, is the result of favorable resolution of uncertain tax positions.

Reconciliation of Non-GAAP Financial Measures

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 21 states, Puerto Rico, and internationally.  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, including the impacts of potential sequestration under the Budget Control Act of 2011, 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 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.

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ALLIANT TECHSYSTEMS INC.

CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME

(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)