Exhibit 99.1

ATK Reports First-Quarter Operating Results

ATK Delivers Strong Operating Margins of 12.1 Percent

ATK Increases Full-Year FY12 EPS Guidance

Minneapolis, August 4, 2011 — ATK (NYSE: ATK) today reported operating results for the first quarter of its Fiscal Year 2012, which ended on July 3, 2011.  Fully diluted earnings per share were $2.13, compared to $2.24 in the prior-year period.  First quarter results included a one-time discrete tax benefit of $0.11 per share. Margins in the first quarter improved to 12.1 percent compared to 11.1 percent in the prior-year quarter.  The increase reflects a continued focus on efficiency improvements and cost management initiatives throughout the company, and a one-time gain related to the sale of a non-essential parcel of land.

First quarter sales of $1.1 billion were down from the $1.2 billion recorded in the prior-year, reflecting lower sales on NASA’s human space flight programs, as well as lower sales of non-standard ammunition and lower sales at the Radford Army Ammunition Plant.  Net income for the quarter was $72 million compared to $75 million in the prior-year quarter.

Based on sustainable margin improvements and a lower share count resulting from a $50 million share repurchase, the company is raising its full-year EPS guidance.

“Our aggressive focus on efficiency improvements and cost management contributed to the strength of our bottom-line results, even in the face of a challenging sales environment,” said Mark DeYoung, President and CEO. “We are meeting key production and delivery milestones, executing on our programs of record, and winning new business including the recently-announced Joint Allied Threat Awareness System (JATAS) program.”

SUMMARY OF REPORTED RESULTS

The following table presents the company’s results for the first quarter of the fiscal year which ended July 3, 2011 (in thousands).

Sales:

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

SEGMENT RESULTS

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

AEROSPACE SYSTEMS

First quarter sales fell four percent to $354 million, compared to $369 million in the prior-year period.  The decrease reflects lower revenue on NASA programs, partially offset by higher sales of commercial aircraft structures and flares/decoys.

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Earnings before interest, taxes, and noncontrolling interest (operating profit) in the quarter rose 19 percent to $43 million, compared to $36 million in the prior-year quarter.  The increase reflects a $5.4 million gain from the sale of a non-essential parcel of land to the State of Utah, additional profit generated by higher sales volumes of flares and decoys, and improved operating efficiencies.  These were partially offset by lower sales on the group’s NASA human space flight programs.

ARMAMENT SYSTEMS

Sales in the first quarter declined by 21 percent to $347 million, compared to $439 million in the prior-year quarter.  The decrease was driven primarily by lower non-standard ammunition and weapons sales, and lower sales at the group’s Radford, Virginia facility.

Operating profit for the quarter declined by four percent to $48 million, compared to $50 million in the prior-year quarter, driven by lower sales volume as noted above, partially offset by improved operating efficiencies.

MISSILE PRODUCTS

Sales in the first quarter declined by seven percent to $145 million, compared to $156 million in the prior-year quarter. The decrease primarily reflects lower sales volume in defense electronics due primarily to the timing of awards.

Operating profit of $17 million remained consistent with the prior-year quarter.  A continued focus on improving operating efficiencies and a higher profit rate on tactical rocket motor programs offset lower sales volumes.

SECURITY AND SPORTING

First quarter sales decreased by four percent to $229 million, compared to $238 million in the prior-year quarter.  The decrease in sales volume was primarily the result of advanced sales of commercial ammunition in the fourth quarter of FY11 due to the price increase implemented in the first quarter of FY12.

Operating profit in the first quarter decreased by 11 percent to $29 million, compared to $33 million in the prior-year quarter, reflecting lower sales volume in commercial ammunition products and increased raw material costs.

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CORPORATE AND OTHER

In the first quarter, corporate and other expenses totaled $6 million, compared to expenses of $2 million in the prior-year quarter, reflecting increased pension expense and higher inter-company profit eliminations which are recorded within corporate. The tax rate for the quarter was 31.2 percent compared to 35.2 percent in the prior-year quarter, which reflects a one-time benefit from a recent state tax law change.  Interest expense was $26.3 million compared to $17.6 million in the prior-year quarter, which reflects the additional debt issued in October, 2010.  Free cash flow of negative $193 million in the first quarter reflects a normal seasonal increase in working capital, and pension contributions of approximately $62 million (see reconciliation table for details). During the quarter, the company repurchased $50 million of common stock and retired $50 million of the convertible notes due in September, 2011.

OUTLOOK

Based on better visibility into the remainder of the year, the company is raising its full-year FY12 EPS guidance to a range of $8.50 to $9.00 from the previously announced range of $8.00 to $8.60.  ATK continues to expect full-year sales in a range from $4.6 to $4.8 billion.

ATK now expects an average share count for the full year of approximately 33.5 million. The company continues to expect a tax rate for the full year of approximately 34 percent and pension expense of approximately $135 million. ATK continues to expect FY12 cash provided by operating activities in a range of $355 million to $380 million, which includes the impact of a first quarter pension contribution of approximately $62 million.  The company expects capital expenditures of approximately $130 million and free cash flow in a range of $225 million — $250 million (see reconciliation table for details).

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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 acquisitions, debt repayment, cash dividends, and share repurchase 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; 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; increases in commodity costs, energy prices, and production costs; the terms and timing of awards and contracts; program performance; program

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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 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 INCOME STATEMENTS

(preliminary and unaudited)

ALLIANT TECHSYSTEMS INC.

CONDENSED CONSOLIDATED BALANCE SHEETS

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ALLIANT TECHSYSTEMS INC.

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

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