SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                _______________

                                  SCHEDULE TO

           Tender Offer Statement under Section 14(d)(1) or 13(e)(1)
                     of the Securities Exchange Act of 1934

                               (Amendment No. 4)

                            LITTON INDUSTRIES, INC.

                       (Name of Subject Company (issuer))

                          NORTHROP GRUMMAN CORPORATION
                             LII ACQUISITION CORP.

                       (Name of Filing Persons (offeror))

                    Common Stock, Par Value $1.00 Per Share
                         (including associated rights)
                         (Title of Class of Securities)

                                 538021 10 6
                     (CUSIP Number of Class of Securities)

       Series B $2 Cumulative Preferred Stock, Par Value $5.00 Per Share

                         (Title of Class of Securities)

                                  538021 40 3

                     (CUSIP Number of Class of Securities)

                                 W. Burks Terry
                  Corporate Vice President and General Counsel
                          Northrop Grumman Corporation
                             1840 Century Park East
                         Los Angeles, California  90067
                                 (310) 553-6262

  (Name, Address and Telephone Number of Person Authorized to Receive Notices
        and Communications on Behalf of the Person(s) Filing Statement)

                                    Copy to:

                                Andrew E. Bogen
                         Gibson, Dunn & Crutcher LLP
                            333 South Grand Avenue
                      Los Angeles, California  90071-3197
                                (213) 229-7159

[ ] Check the box if the filing relates solely to preliminary communications
    made before the commencement of a tender offer.

[ ] Check the appropriate boxes to designate any transactions to which this
    statement relates:

      [X] third party tender offer           [ ] going-private transaction
              subject to Rule 14d-1                    subject to Rule 13e-3

      [ ] issuer tender offer                [ ] amendment to Schedule 13D
              subject to Rule 13e-4                    under Rule 13d-2


     Check the following box if the filing is a final amendment reporting the
     results of the tender offer.   [ ]



        Northrop Grumman Corporation, a Delaware corporation ("Parent"), and
LII Acquisition Corp., a Delaware corporation ("LII Acquisition") and wholly
owned subsidiary of Parent, hereby amend and supplement their Tender Offer
Statement on Schedule TO originally filed on January 5, 2001 (the "Schedule
TO"), as subsequently amended from time to time, with respect to Purchaser's
Offer to Purchase (a) all of the issued and outstanding shares of common stock,
par value $1.00 per share (the "Common Stock") of Litton Industries, Inc., a
Delaware corporation (the "Company"), together with any associated rights to
purchase preferred stock of the Company (the "Rights," and, together with the
Common Stock, the "Common Shares") at a price per Common Share of $80.00 (the
"Common Offer Price") and (b) all of the outstanding shares of Series B $2
Cumulative Preferred Stock, par value $5.00 per share (the "Preferred Shares"),
of the Company at a price per Preferred Share of $35.00 (the "Preferred Offer
Price" and, together with the Common Offer Price, the "Offer Price").
Capitalized terms used but not defined herein have the respective meanings
assigned to such terms in the Schedule TO and the Offer to Purchase dated
January 5, 2001, filed as Exhibit (a)(1)(i) thereto.

        Attached as exhibits to this Amendment No. 4 are three additional
material agreements executed in connection with the tender offer described
in the Schedule TO, as amended from time to time, including:

        .     Amended and Restated Agreement and Plan of Merger dated January
              23, 2001 (the "Amended Merger Agreement") and executed and
              delivered by Parent, the Company, NNG, Inc., a Delaware
              corporation ("NNG"), and LII Acquisition on January 24, 2001.

        .     Stockholder's Agreement dated as of January 23, 2001 and
              executed and delivered by Parent, NNG and Unitrin, Inc. on January
              24, 2001.

        .     Registration Rights Agreement dated as of January 23, 2001 and
              executed and delivered by Parent, NNG and Unitrin, Inc. on January
              24, 2001.

        The Amended Merger Agreement amends the terms of the tender offer
described in the Schedule TO to provide, among other things, a choice of cash or
stock of a new subsidiary of Parent for tendering holders of Common Shares.  The
Stockholders Agreement provides for the tender of all of the Common Shares owned
by Unitrin, Inc., a substantial shareholder of the Company, and the Registration
Rights Agreement provides for certain rights of Unitrin to have Securities
received in the offer registered under the Securities Act of 1933, as amended.
The material terms of each of these agreements are summarized in an offer to
purchase or exchange/prospectus to be filed shortly as part of a Registration
Statement on Form S-4. The offer to purchase or exchange/prospectus will be
distributed to all Litton stockholders in connection with the extension and
amendment of the tender offer described in the Schedule TO, as amended.

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Item 12. Exhibits

     Item 12 of the Schedule TO is hereby amended and supplemented to include
the following exhibits:

     (d)(4)   Amended and Restated Agreement and Plan of Merger dated as of
January 23, 2001 among Northrop Grumman Corporation, Litton Industries, Inc.,
NNG, Inc. and LII Acquisition Corp.

     (d)(5)   Stockholder's Agreement dated as of January 23, 2001 among
Northrop Grumman Corporation, NNG, Inc. and Unitrin, Inc.

     (d)(6)   Registration Rights Agreement dated as of January 23, 2001 by and
among Northrop Grumman Corporation, NNG, Inc. and Unitrin, Inc.

                                       3


                                   SIGNATURE

     After due inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.


                              LII ACQUISITION CORP.


                              By:  /s/ John H. Mullan
                                 -------------------------------------------
                              Name: John H. Mullan
                                   -----------------------------------------
                              Title: Secretary
                                    ----------------------------------------


                              NORTHROP GRUMMAN CORPORATION


                              By:  /s/ John H. Mullan
                                 ------------------------------------------
                              Name: John H. Mullan
                                   ----------------------------------------
                              Title: Corporate Vice President and Secretary
                                    ---------------------------------------


Dated: January 31, 2001

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                                 EXHIBIT INDEX



(a)(1)(i)*    Offer to Purchase, dated January 5, 2001.

(a)(1)(ii)*   Letter of Transmittal, Common Stock and Preferred Stock, each
              dated January 5, 2001.

(a)(1)(iii)*  Notice of Guaranteed Delivery, Common Stock and Preferred Stock,
              each dated January 5, 2001.

(a)(1)(iv)*   Notice to Participants in the Litton Industries Employees Stock
              Purchase Plan prior to December 1, 1993, dated January 5, 2001.

(a)(1)(v)*    Notice to Participants in the Litton Industries Employees Stock
              Purchase Plan after November 1, 1994, dated January 5, 2001.

(a)(2)        None.

(a)(3)        Not applicable.

(a)(4)        Not applicable.

(a)(5)(i)*    Letter to Brokers, Dealers, Commercial Banks, Trust Companies and
              other Nominees, Common Stock and Preferred Stock, dated January 5,
              2001.

(a)(5)(ii)*   Letter to Clients, Common Stock and Preferred Stock, each dated
              January 5, 2001.

(a)(5)(iii)*  Guidelines for Certification of Taxpayer Identification Number on
              Substitute Form W-9.

(a)(5)(iv)*   Press release issued by Parent on December 21, 2000 (incorporated
              by reference to Schedule TO-C filed with the Securities and
              Exchange Commission on December 20, 2000).

(a)(5)(v)*    Summary Advertisement as published in the Wall Street Journal on
              January 5, 2001.

(a)(5)(vi)*   Press release issued by Parent on January 8, 2001.

(a)(5)(vii)*  Press release issued by Parent on January 16, 2001.

(a)(5)(viii)* Joint Press release issued by Parent and the Company on
              January 24, 2001.

(b)(i)*       Financing Commitment Letter dated December 20, 2000 from Credit
              Suisse First Boston and The Chase Manhattan Bank relating to
              $6,000,000,000 aggregate principal amount of senior credit
              facilities.

(c)           Not applicable.

(d)(1)*       Merger Agreement, dated as of December 21, 2000, by and among
              Parent, Purchaser and the Company.

(d)(2)*       Confidentiality Agreement dated June 23, 2000, between Parent and
              the Company.

(d)(3)*       Letter Agreement dated December 21, 2000, between Ronald D. Sugar
              and Parent.

(d)(4)        Amended and Restated Agreement and Plan of Merger dated as of
              January 23, 2001 among Northrop Grumman Corporation, Litton
              Industries, Inc., NNG, Inc. and LII Acquisition Corp.

(d)(5)        Stockholder's Agreement dated as of January 23, 2001 among
              Northrop Grumman Corporation, NNG, Inc. and Unitrin, Inc.

(d)(6)        Registration Rights Agreement dated as of January 23, 2001 by and
              among Northrop Grumman Corporation, NNG, Inc. and Unitrin, Inc.

(e)           Not applicable.

(f)*          Section 262 of the Delaware General Corporation Law (included as
              Schedule II to the Offer to Purchase).

(g)           None.

(h)           None.

*  Previously filed.

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