EXHIBIT 99.4


                          THIRD SUPPLEMENTAL INDENTURE

                  This Third Supplemental Indenture, dated as of December 31,
2005 (this "Supplemental Indenture"), among Ispat Inland ULC, a Nova Scotia
unlimited liability company (the "Issuer"), the Guarantors, Mittal Steel USA ISG
Inc. ("ISG") and LaSalle Bank National Association, as Trustee under the
Indenture referred to below.

                                   WITNESSETH:

                  WHEREAS, the Issuer, the Guarantors and the Trustee have
heretofore executed and delivered an Indenture, dated as of March 25, 2004 (as
heretofore amended, supplemented, waived or otherwise modified, the
"Indenture"), providing for the issuance of Senior Secured Floating Rate Notes
due 2010 and 9 3/4% Senior Secured Notes due 2014 of the Issuer (together, the
"Notes");

                  WHEREAS, Ispat Inland Inc. ("Inland"), a Guarantor under the
Indenture, will be merging with and into ISG, with ISG as the Successor Company;

                  WHEREAS, Section 5.01(a) of the Indenture requires that upon a
merger of Inland with or into another Person, the Successor Company shall
execute and deliver a supplemental indenture pursuant to which such Successor
Company will expressly assume all of the obligations of Inland under the
Mortgage, the First Mortgage Bonds, Inland's Note Guarantee and the Indenture;

                  WHEREAS, pursuant to Section 8.01 of the Indenture, the
Issuer, the Guarantors and the Trustee are authorized to execute and deliver
this Supplemental Indenture to amend or supplement the Indenture, without the
consent of any Holder;

                  WHEREAS, this Supplemental Indenture has been duly authorized
by all necessary corporate action on the part of each of the Issuer, the
Guarantors and the Trustee;

                  NOW, THEREFORE, in consideration of the foregoing and for
other good and valuable consideration, the receipt of which is hereby
acknowledged, the Issuer, the Guarantors and the Trustee mutually covenant and
agree for the equal and ratable benefit of the Holders of the Notes as follows:

                                    ARTICLE I

                                   DEFINITIONS

                  SECTION 1.1 Defined Terms. As used in this Supplemental
Indenture, terms defined in the Indenture or in the preamble or recital hereto
are used herein as therein defined. The words "herein," "hereof" and hereby" and
other words of similar import used in this Supplemental Indenture refer to this
Supplemental Indenture as a whole and not to any particular section hereof.


                                        1



                                   ARTICLE II

                                ASSUMPTION BY ISG

                  SECTION 2.1 Agreement to be Bound as Guarantor. ISG hereby
becomes a party to the Indenture as the Successor Company of Inland, as
Guarantor of the Notes, and as such succeeds to, and is substituted for, and may
exercise every right and power of, Inland under the Indenture and shall be
subject to all of the obligations and agreements of Inland under the Indenture.
ISG agrees to be bound by all of the provisions of the Indenture, the Mortgage,
the First Mortgage Bonds and Inland's Note Guarantee applicable to Inland, and
expressly assumes and agrees to perform all of the obligations and agreements of
Inland under the Indenture, the Mortgage, the First Mortgage Bonds and Inland's
Note Guarantee.

                  SECTION 2.2 Trustee's Acceptance. The Trustee hereby agrees to
accept this Supplemental Indenture and agrees, from and after the effective time
of this Supplemental Indenture, to perform the same under the terms and
conditions set forth in the Indenture.

                                   ARTICLE III

                                  MISCELLANEOUS

                  SECTION 3.1 Notices. All notices and other communications to
the Issuer or any Guarantor shall be given in the manner provided in the
Indenture to the Issuer or such Guarantor at the address set forth below:

                  Mittal Steel USA Inc.
                  4020 Kin Ross Lakes Parkway
                  Richfield, OH 44286
                  Attention: General Counsel
                  Fax: (330) 659-7626

                  With copies to:

                  Shearman & Sterling LLP
                  Broadgate West
                  9 Appold Street
                  London, United Kingdom
                  EC2A 2AP
                  Attention:  Richard J.B. Price
                  Fax:  +44 20 7655 5485

                  and to:

                  Mayer Brown Rowe & Maw LLP
                  190 South LaSalle Street
                  Chicago, IL  60603
                  Attention:  J. Trent Anderson
                  Fax:  (312) 706-8101


                                        2


                  SECTION 3.2 Benefits of Supplemental Indenture. Nothing
expressed or mentioned herein is intended or shall be construed to give any
Person, firm or corporation, other than the parties hereto and their successors
hereunder and the Holders, any legal or equitable right, remedy or claim under
or in respect of this Supplemental Indenture or the Indenture or any provision
herein or therein contained.

                  SECTION 3.3 Governing Law. This Supplemental Indenture shall
be governed by, and construed in accordance with, the laws of the State of New
York.

                  Section 3.4 Ratification of Indenture; Supplemental Indenture
Part of Indenture. Except as expressly amended hereby, the Indenture is in all
respects ratified and confirmed and all the terms, conditions and provisions
thereof shall remain in full force and effect. This Supplemental Indenture shall
form a part of the Indenture for all purposes, and every Holder of Notes
heretofore or hereafter authenticated and delivered shall be bound hereby. The
Trustee makes no representation or warranty as to the validity or sufficiency of
this Supplemental Indenture.

                  SECTION 3.5 Counterparts. The parties hereto may sign one or
more copies of this Supplemental Indenture in counterparts, all of which
together shall constitute one and the same agreement.

                  SECTION 3.6 Headings. The headings of the Articles and the
Sections in this Supplemental Indenture are for convenience of reference only
and shall not be deemed to alter or affect the meaning or interpretation of any
provisions hereof.

                  SECTION 3.7 Trust Indenture Act Controls. If and to the extent
that any provision of this Indenture limits, qualifies or conflicts with another
provision which is required to be included in this Supplemental Indenture by the
TIA, the provision required by the TIA shall control.

                  SECTION 3.8 Severability. In case any provision in this
Supplemental Indenture shall be invalid, illegal or unenforceable, the validity,
legality and enforceability of the remaining provisions shall not in any way be
affected or impaired thereby.

                  SECTION 3.9 Successors. All agreements of ISG in this
Supplemental Indenture shall bind its successors. All agreements of the Trustee
in this Supplemental Indenture shall bind its successors.



               [Page Intentionally Left Blank; Signatures Follow]


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                  IN WITNESS WHEREOF, the parties hereto have caused this
Supplemental Indenture to be duly executed as of the date first above written.

                                    ISPAT INLAND U.L.C.,
                                    as Issuer


                                    By: /s/ Richard Leblanc
                                        ---------------------------------
                                        Name:  Richard Leblanc
                                        Title: Secretary



                                    MITTAL STEEL USA ISG INC.,
                                    as Successor Company


                                    By: /s/ Carlos M. Hernandez
                                        ---------------------------------
                                        Name:  Carlos M. Hernandez
                                        Title: General Counsel and Secretary



                                    MITTAL STEEL COMPANY N.V.,
                                    as Guarantor


                                    By: /s/ H.J. Scheffer_
                                        ---------------------------------
                                        Name:  H.J. Scheffer
                                        Title: Company Secretary



                                    ISPAT INLAND INC.,
                                    as Guarantor


                                    By: /s/ T.A. McCue
                                        ---------------------------------
                                        Name:  T.A. McCue
                                        Title: Treasurer




                                    BURNHAM TRUCKING COMPANY, INC.,
                                    as Guarantor


                                    By: /s/ T.A. McCue
                                        ---------------------------------
                                        Name:  T.A. McCue
                                        Title: Treasurer






                                    INCOAL COMPANY,
                                    as Guarantor


                                    By: /s/ Marc R. Jeske
                                        ---------------------------------
                                        Name:  M.R. Jeske
                                        Title: Secretary



                                    ISPAT INLAND MINING COMPANY,
                                    as Guarantor


                                    By: /s/ T.A. McCue
                                        ---------------------------------
                                        Name:  T.A. McCue
                                        Title: Treasurer



                                    ISPAT INLAND SERVICE CORP.,
                                    as Guarantor


                                    By: /s/ T.A. McCue
                                        ---------------------------------
                                        Name:  T.A. McCue
                                        Title: Treasurer



                                    ISPAT INLAND, L.P.,
                                    as Guarantor


                                    By: /s/ Denis Fraser
                                        ---------------------------------
                                        Name:  Denis Fraser
                                        Title: Director



                                    3019693 NOVA SCOTIA U.L.C.,
                                    as Guarantor


                                    By: /s/ Richard Leblanc
                                        ---------------------------------
                                        Name:  Richard Leblanc
                                        Title: Secretary






                                    ISPAT INLAND FINANCE, LLC,
                                    as Guarantor


                                    By: /s/ T.A. McCue
                                        ---------------------------------
                                        Name:  T.A. McCue
                                        Title: Manager


                                    LASALLE BANK NATIONAL ASSOCIATION,
                                    as Trustee


                                    By: /s/ Gregory S. Clarke
                                        ---------------------------------
                                        Name:  Gregory S. Clarke
                                        Title: Vice President