Exhibit 5(a)

+1 202 663 6000 (t)

+1 202 663 6363 (f)

wilmerhale.com

July 27, 2011

Northrop Grumman Corporation

1840 Century Park East

Los Angeles, California 90067

Re: Registration Statement on Form S-3

Ladies and Gentlemen:

This opinion is furnished to you in connection with a Registration Statement on Form S-3 (the “Registration Statement”) filed by Northrop Grumman Corporation, a Delaware corporation (the “Company”), with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”), for the registration of the following securities of the Company (the “Securities”):

(i) common stock, $1.00 par value per share (the “Common Stock”); and

(ii) senior debt securities (the “Senior Debt Securities”),

all of which may be issued from time to time on a delayed or continuous basis pursuant to Rule 415 under the Securities Act at an indeterminate aggregate initial offering price, as set forth in the Registration Statement, the prospectus contained therein (the “Prospectus”) and any amendments or supplements thereto.

We are acting as counsel for the Company in connection with the filing of the Registration Statement. The Senior Debt Securities may be issued, in one or more series, pursuant to the Indenture, dated as of November 21, 2001, between the Company and The Bank of New York Mellon Trust Company, N.A., as trustee, (as amended and/or supplemented from time to time, the “Indenture”), which has been duly qualified under the Trust Indenture Act of 1939, as amended (the “Trust Indenture Act”).

We have examined and relied upon signed copies of the Registration Statement to be filed with the Commission, including the exhibits thereto. We have also examined and relied upon the corporate minute books of the Company as provided to us by the Company, the Restated Certificate of Incorporation of the Company (as amended and/or restated from time-to-time, the “Certificate of Incorporation”) and the Restated Bylaws of the Company (as restated and/or amended from time-to-time, the “Bylaws”), and such other documents as we have deemed necessary for purposes of rendering the opinions hereinafter set forth.

In our examination of the documents described above, we have assumed the genuineness of all signatures, the legal capacity of all individual signatories, the authenticity of all documents

Wilmer Cutler Pickering Hale and Dorr LLP, 1875 Pennsylvania Avenue NW, Washington, DC 20006

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Northrop Grumman Corporation

July 27, 2011

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submitted to us as originals, the conformity to original documents of all documents submitted to us as copies, the authenticity of such original documents and the completeness and accuracy of the corporate minute books of the Company provided to us by the Company.

We have relied as to certain matters on information obtained from public officials and officers of the Company, and we have assumed that (i) one or more Prospectus supplements will be prepared and filed with the Commission describing the Securities offered thereby, (ii) all Securities will be issued and sold in compliance with applicable federal and state securities laws and in the manner stated in the Registration Statement, the Prospectus and the applicable Prospectus supplements, (iii) the Indenture will be duly authorized, executed and delivered by the trustee named therein, (iv) the trustee named in the Indenture will be duly qualified under the Trust Indenture Act, (v) the Senior Debt Securities offered will be duly authenticated by the trustee named in the Indenture, (vi) a definitive purchase, underwriting or similar agreement (the “Purchase Agreement”) with respect to any Securities offered will be duly authorized, executed and delivered by all parties thereto, (vii) any Securities issuable upon conversion, exchange or exercise of any Security being offered will be duly authorized, created and, if appropriate, reserved for issuance upon such conversion, exchange or exercise, (viii) with respect to shares of Common Stock offered, there will be sufficient shares of Common Stock authorized under the Company’s Certificate of Incorporation and not otherwise reserved for issuance and (ix) the Company will be validly existing as a corporation and in good standing under the laws of the State of Delaware.

We are expressing no opinion herein as to the application of, or compliance with, any foreign, federal or state law or regulation to the power, authority or competence of any party to any agreement with respect to any of the Securities other than the Company. We have assumed that such agreements are, or will be, the valid and binding obligations of each party thereto other than the Company, and enforceable against each such other party in accordance with their respective terms.

We have assumed for purposes of our opinions below that no authorization, approval or other action by, and no notice to or filing with, any governmental authority or regulatory body or any other third party is required for the due execution, delivery or performance by the Company or, if any such authorization, approval, consent, action, notice or filing is required, it will have been duly obtained, taken, given or made and will be in full force and effect. We have also assumed that the execution and delivery by the Company of the Indenture, the Purchase Agreement and the Securities and the performance by the Company of its obligations thereunder do not and will not violate, conflict with or constitute a default under (i) any agreement or instrument to which the Company or any of its properties is subject, (ii) any law, rule or regulation to which the Company or any of its properties is subject or (iii) any judicial or regulatory order or decree of any governmental authority.

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July 27, 2011

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We have also assumed that there will not have occurred, prior to the date of issuance of the Securities, any change in law affecting the validity or enforceability of such Securities and that at the time of the issuance and sale of the Securities, the Board of Directors of the Company (or any committee thereof acting pursuant to authority properly delegated to such committee by the Board of Directors) shall not have taken any action to rescind or otherwise reduce its prior authorization of the issuance of the Securities.

Our opinions below are qualified to the extent that they may be subject to or affected by (i) applicable bankruptcy, insolvency, reorganization, moratorium, usury, fraudulent conveyance or similar laws relating to or affecting the rights or remedies of creditors generally, (ii) duties and standards imposed on creditors and parties to contracts, including, without limitation, requirements of materiality, good faith, reasonableness and fair dealing and (iii) general equitable principles. Furthermore, we express no opinion as to the availability of any equitable or specific remedy upon any breach of any of the agreements as to which we are opining herein, or any of the agreements, documents or obligations referred to therein, or to the successful assertion of any equitable defenses, inasmuch as the availability of such remedies or the success of any equitable defenses may be subject to the discretion of a court. We also express no opinion herein as to the laws of any state or jurisdiction other than the state laws of the State of New York, the General Corporation Law of the State of Delaware and the federal laws of the United States of America. We express no opinion herein with respect to compliance by the Company with securities or “blue sky” laws of any state or other jurisdiction of the United States or of any foreign jurisdiction. In addition, we express no opinion and make no statement herein with respect to the antifraud laws of any jurisdiction.

We also express no opinion herein as to any provision of any agreement (i) that may be deemed to or construed to waive any right of the Company, (ii) to the effect that rights and remedies are not exclusive, that every right or remedy is cumulative and may be exercised in addition to or with any other right or remedy and does not preclude recourse to one or more other rights or remedies, (iii) relating to the effect of invalidity or unenforceability of any provision of any agreement on the validity or enforceability of any other provision thereof, (iv) that is in violation of public policy, (v) relating to indemnification and contribution with respect to securities law matters, (vi) which provides that the terms of any agreement may not be waived or modified except in writing, (vii) purporting to indemnify any person against his, her or its own negligence or intentional misconduct, (viii) requiring the payment of penalties, consequential damages or liquidated damages or (ix) relating to choice of law or consent to jurisdiction.

Based upon and subject to the foregoing, we are of the opinion that:

1. With respect to the Common Stock, when (i) specifically authorized for issuance by proper action of the Company’s Board of Directors or an authorized committee thereof (the “Authorizing Resolutions”), (ii) the terms of the issuance and sale of the Common Stock have been duly established in conformity with the Company’s Certificate of Incorporation, Bylaws

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July 27, 2011

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and Authorizing Resolutions, (iii) the shares of Common Stock have been issued and sold as contemplated by the Registration Statement, the Prospectus and the applicable supplements to such Prospectus and (iv) the Company has received the consideration provided for in the Authorizing Resolutions and such consideration per share is not less than the par value per share of Common Stock, the Common Stock will be validly issued, fully paid and nonassessable.

2. With respect to the Senior Debt Securities, when (i) specifically authorized for issuance by the Authorizing Resolutions, (ii) the terms of the Senior Debt Securities and of their issuance and sale have been duly established in conformity with the Indenture and the Authorizing Resolutions, (iii) such Senior Debt Securities have been duly executed and authenticated in accordance with the Indenture and issued and sold as contemplated by the Registration Statement, the Prospectus and the applicable supplements to such Prospectus and (iv) the Company has received the consideration provided for in the Authorizing Resolutions, such Senior Debt Securities will constitute valid and binding obligations of the Company, enforceable against the Company in accordance with their terms.

Please note that we are opining only as to the matters expressly set forth herein, and no opinion should be inferred as to any other matters. This opinion is based upon currently existing statutes, rules, regulations and judicial decisions, and we disclaim any obligation to advise you of any change in any of these sources of law or subsequent legal or factual developments which might affect any matters or opinions set forth herein.

We hereby consent to the filing of this opinion with the Commission as an exhibit to the Registration Statement in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Securities Act and to the use of our name therein and in the related Prospectus and any Prospectus supplement under the caption “Legal Matters.” In giving such consent, we do not hereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission.

Very truly yours,

WILMER CUTLER PICKERING

HALE AND DORR LLP

By:	/s/ Erika L. Robinson
	Erika L. Robinson, a Partner