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Exhibit (a)(1)(D)

Offer To Purchase For Cash
All Outstanding Shares of Common Stock
of
ARGON ST, INC.

at
$34.50 NET PER SHARE
Pursuant to the Offer to Purchase dated July 8, 2010
by

VORTEX MERGER SUB, INC.,
a wholly owned subsidiary of
THE BOEING COMPANY

THE OFFER AND WITHDRAWAL RIGHTS WILL EXPIRE AT 12:00 MIDNIGHT, NEW YORK CITY TIME, AT THE END OF THE DAY ON AUGUST 4, 2010, UNLESS THE OFFER IS EXTENDED (SUCH DATE AND TIME AS IT MAY BE EXTENDED, THE “EXPIRATION DATE”) OR EARLIER TERMINATED.

July 8, 2010

To Brokers, Dealers, Commercial Banks, Trust Companies and Other Nominees:

We have been engaged by Vortex Merger Sub, Inc., a Delaware corporation (the “Purchaser”) and a wholly owned subsidiary of The Boeing Company, a Delaware corporation (“Parent”), to act as the Information Agent in connection with the Purchaser’s offer to purchase (the “Offer”) all of the outstanding shares of common stock, par value $0.01 per share (the “Shares”), of Argon ST, Inc., a Delaware corporation (“Argon”), at a purchase price of $34.50 per Share, net to the seller in cash, without interest thereon and less any applicable withholding taxes, upon the terms and subject to the conditions set forth in the Offer to Purchase, dated July 8, 2010 (the “Offer to Purchase”), and the related Letter of Transmittal enclosed herewith.

The Offer is being made pursuant to an Agreement and Plan of Merger, dated as of June 30, 2010 (as it may be amended from time to time, the “Merger Agreement”), among Parent, the Purchaser and Argon. The Merger Agreement provides, among other things, that following the consummation of the Offer and subject to certain conditions, the Purchaser will be merged with and into Argon (the “Merger”), with Argon continuing as the surviving corporation and wholly owned by Parent. In the Merger, each Share outstanding immediately prior to the effective time of the Merger (other than Shares held (i) in the treasury of Argon or any of its subsidiaries or by Parent or the Purchaser, which Shares shall be canceled and shall cease to exist, or (ii) by stockholders who validly exercise appraisal rights under Delaware law with respect to such Shares) will be canceled and converted into the right to receive the Offer Price, without interest thereon and less any applicable withholding taxes. The Merger Agreement is more fully described in the Offer to Purchase, dated July 8, 2010.

The Argon board of directors, among other things, has unanimously (i) approved and declared advisable the Merger Agreement, the Offer, the Merger and the other transactions contemplated by the Merger Agreement, (ii) declared that it is in the best interests of Argon and the stockholders of Argon (other than Parent and its subsidiaries) that Argon enter into the Merger Agreement and consummate the Merger and the other transactions contemplated by the Merger Agreement and that the stockholders of Argon tender their Shares pursuant to the Offer, in each case on the terms and subject to the conditions set forth in the Merger Agreement, (iii) declared that the terms of the Offer and the Merger are fair to Argon and Argon’s stockholders (other than Parent and its subsidiaries) and (iv) recommended that Argon’s stockholders accept the Offer, tender their Shares pursuant to the Offer and, if required by applicable law, adopt the Merger Agreement.

For your information and for forwarding to your clients for whom you hold Shares registered in your name or in the name of your nominee, we are enclosing the following documents:

1. The Offer to Purchase;

2. The related Letter of Transmittal for your use in accepting the Offer and tendering Shares and for the information of your clients, together with “Guidelines for Certification of Taxpayer Identification Number on Substitute Form W — 9” providing information relating to backup federal income tax withholding;

3. The Notice of Guaranteed Delivery to be used to accept the Offer if share certificates for such Shares (the “Share Certificates”) are not immediately available or time will not permit all required documents to reach American Stock Transfer and Trust Company (the “Depositary”) on or before the Expiration Date or the procedures for book-entry transfer cannot be completed on or before the Expiration Date;

4. Argon’s Solicitation/Recommendation Statement on Schedule 14D-9 and accompanying letter from Argon, in each case filed with the U.S. Securities and Exchange Commission;

5. A form of letter which may be sent to your clients for whose accounts you hold Shares registered in your name or in the name of your nominee, with space provided for obtaining such clients’ instructions with regard to the Offer; and

6. A return envelope addressed to the Depositary for your use only.

The Offer is conditioned upon, among other things, the Merger Agreement not being terminated in accordance with its terms and each of (i) the Minimum Tender Condition (as described below), (ii) the Competition Law Condition (as described below) and (iii) the Governmental Entity Condition (as described below) being satisfied. The Minimum Tender Condition requires that the number of Shares that have been validly tendered and not validly withdrawn prior to the then scheduled Expiration Date, together with the number of Shares (if any) then owned by Parent and its subsidiaries, represents at least a majority of the total number of outstanding Shares on a fully diluted basis. The Competition Law Condition requires the expiration or termination of any waiting period (and any extensions thereof) applicable to the transactions contemplated by the Merger Agreement under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and any other applicable federal, state or foreign statute, rule, regulation, order, decree, administrative or judicial doctrine or other law that is designed or intended to prohibit, restrict or regulate actions having the purpose or effect of monopolization, restraint of trade, lessening of competition or foreign investment. The Governmental Entity Condition requires that no governmental entity shall have enacted, enforced, amended or issued any law or judgment which is then in effect and has the effect of making the Offer or the Merger illegal or otherwise prohibiting or materially delaying the consummation of the Offer or the Merger, and that no claim, suit, action or proceeding shall exist or be instituted by any governmental entity seeking any such consequence. These and other conditions to the Offer are described in Section 15 of the Offer to Purchase.

We urge you to contact your clients as promptly as possible. Please note that the Offer will expire at 12:00 midnight, New York City time, at the end of the day on August 4, 2010, unless the Offer is extended or earlier terminated.

In order for a stockholder to validly tender Shares pursuant to the Offer, the Letter of Transmittal (or a manually signed facsimile thereof), properly completed and duly executed, together with any required signature guarantees (or, in the case of a book-entry transfer, an Agent’s Message (as defined in the Offer to Purchase) in lieu of the Letter of Transmittal) and any other documents required by the Letter of Transmittal must be received by the Depositary and either (A) the share certificates evidencing tendered Shares must be received by the Depositary or (B) such Shares must be tendered pursuant to the procedure for book-entry transfer described in the Offer to Purchase and a Book-Entry Confirmation (as defined in the Offer to Purchase) must be received by the Depositary, in each case prior to the Expiration Date. Alternatively, a stockholder may be able to validly tender such stockholder’s Shares by completing and returning the Notice of Guaranteed Delivery using the procedures described in Section 3 of the Offer to Purchase.

Neither Parent nor the Purchaser will pay any fees or commissions to any broker or dealer or any other person (other than to the Depositary and Information Agent as described in the Offer to Purchase) in connection with the solicitation of tenders of Shares pursuant to the Offer. The Purchaser will, however, upon request, reimburse brokers, dealers, commercial banks and trust companies for customary mailing and handling expenses incurred by them in forwarding offering materials

to their customers. The Purchaser will pay all stock transfer taxes applicable to its purchase of Shares pursuant to the Offer, subject to Instruction 6 of the Letter of Transmittal.

Any inquiries you may have with respect to the Offer should be addressed to, and additional copies of the enclosed materials may be obtained from, the Information Agent at the address and telephone numbers set forth on the back cover of the Offer to Purchase.

Very truly yours,
Innisfree M&A Incorporated

Nothing contained herein or in the enclosed documents shall render you the agent of the Purchaser, the Information Agent or the Depositary or any affiliate of any of them or authorize you or any other person to use any document or make any statement on behalf of any of them in connection with the Offer other than the enclosed documents and the statements contained therein.