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EX-21.1 5 exhibit211-sx1shelf.htm EX-21.1 Amentum Holdings, Inc - Subsidiaries of the Registrant.
Exhibit 21.1
Entity NameState or Country of Incorporation or Organization
AC First, LLCDelaware
Advanced Range Enterprise Solutions LLCDelaware
Advanced Range Enterprise Solutions LLCDelaware
Aeroptic, LLCMassachusetts
Afghan Holdco LLCDelaware
Africa Expeditionary Services LLCDelaware
AGS Sudan LimitedSouth Sudan
Airport & MRO Facilities Nigeria LimitedNigeria
Alkali Metal Processing LimitedUnited Kingdom
Alliance for Space Communications to Enable New Discovery, LLCFlorida
Amazon Finance LLCDelaware
Amentum (UK) Ltd.United Kingdom
Amentum APAC Pty LimitedAustralia
Amentum Australia Pty LimitedAustralia
Amentum Brazil LtdaBrazil
Amentum Business Support Services Inc.Philippines
Amentum Clean Energy France SASFrance
Amentum Clean Energy LimitedUnited Kingdom
Amentum Clean Energy SA (Pty) LtdSouth Africa
Amentum Commercial Operations, Inc.Delaware
Amentum Digital Infrastructure, Inc.New Jersey
Amentum E&C LimitedUnited Kingdom
Amentum Enterprise Asset Solutions Constructions LimitedUnited Kingdom
Amentum Enterprise Assets Solutions LimitedUnited Kingdom
Amentum Environment & Energy, Inc.Ohio
Amentum Facility Management UK Ltd.United Kingdom
Amentum Global Services - Australia Pty LtdAustralia
Amentum Government Services Holdings LLCDelaware
Amentum Government Services Holdings Sub LLCDelaware



Amentum Government Services Parent Holdings LLCDelaware
Amentum Government Services, Inc.Delaware
Amentum Holdings LLCDelaware
Amentum International Nuclear Services LimitedUnited Kingdom
Amentum International Holdings UK Ltd.United Kingdom
Amentum Japan KKJapan
Amentum Mitie Pacific LLCDelaware
Amentum N&E Holdings LLCDelaware
Amentum N&E UK Holdings LimitedUnited Kingdom
Amentum National Security Programs, Inc.Virginia
Amentum Nuclear & Environment Holdings, Inc.Delaware
Amentum Operaciones ComercialesMexico
Amentum Operaciones Comerciales CRCosta Rica
Amentum Services Canada, Inc.Canada
Amentum Services SDN. BHD.Malaysia
Amentum Services, Inc.Delaware
Amentum Singapore Pte. Ltd.Singapore
Amentum Spaceport LLCDelaware
Amentum Special Mission Services, Inc.Pennsylvania
Amentum SPV LLCDelaware
Amentum Technical Services LLCDelaware
Amentum Technology, Inc.Tennessee
Antarctic Science Alliance LLC Delaware
ASCEND Aerospace and Technology LLCFlorida
Augility Pty LimitedAustralia
Automotive Testing Operations, LLCDelaware
Avicom do Brasil Manutencao de Aeronaves LtdaBrazil
Blue Canopy Group, LLCVirginia
Bravour Leistungen GmbHGermany
Buffalo Group LLCDelaware
Canadian National Energy Alliance Ltd.Canada



Canadian Nuclear Laboratories Ltd.California
Carondelet Energy Readiness LLCDelaware
Casals & Associates, Inc.Virginia
Cavendish Dounreay Partnership LimitedUnited Kingdom
Centra Services CorporationMassachusetts
Centra Technology, Inc.Maryland
CH2M Hill BWXT West Valley, L.L.CDelaware
CH2M HILL GmbHGermany
CH2M Hill IDC SARLFrance
CH2M Hill New York Inc.New York
CH2M HILL Plateau Remediation CompanyWashington
CH2M-WG Idaho, LLCIdaho
CH2M-WG Idaho, LLCIdaho
Courage Services, Inc.Virginia
Critical Mission Services sp. z.o.o (Poland NewCo)Poland
Culpeper National Security Solutions LLCDelaware
Cumbria Nuclear Solutions LimitedUnited Kingdom
Defense Support Services International 3 LLCDelaware
Defense Support Services International, LLCDelaware
Delta Bridge, Inc.Virginia
DTS Aviation Services LLCNevada
DynCorp Aerospace Operations LLCDelaware
DynCorp International Business Services Private LimitedIndia
DynCorp International LLCDelaware
DynCorp International Services GmbHGermany
DynCorp International Services LLCVirginia
DynCorp LLCDelaware
DZSP 21 LLCDelaware
EG&G Defense Materials, Inc.Utah
Energy, Safety & Risk Consultants (UK) LimitedUnited Kingdom



Energy, Security and Technology Canada Ltd.Canada
Energy, Security and Technology LLC (dba ES&T North America)Delaware
Energy, Security and Technology UK LimitedUnited Kingdom
Equitas International LLCDelaware
Expeditionary Logistics Services LLCEgypt
Expeditionary Services Benin LLC Benin
Fast Reactor Technology LimitedUnited Kingdom
Federal Network Systems LLCDelaware
Four Rivers Nuclear Partnership, LLCDelaware
Future Investment Group LLCEgypt
GL Systems LLCDelaware
Global Linguist Solutions LLCDelaware
Global Linguist Solutions Turkey Tercüme Hizmetleri Limited ŞirketiTurkey
Global Management Services GmbHGermany
Global Sourcing SolutionsCayman Islands
Greenline Systems Canada UlcCanada
Jacobs Clean Energy LimitedUnited Kingdom
Jacobs Clean Energy s.r.oCzech Republic
Jacobs Multiconsult Decommissioning ANSNorway
Jacobs Slovakia s.r.o.Slovakia
JT4, LLCDelaware
Lear Siegler Logistics International, Inc.Delaware
Macfadden & Associates, Inc.Virginia
Macfadden International SuarlTunisia
McNeil Security, Inc.Virginia
Mission Conversion Services Alliance, LLCDelaware
Mission Support and Test Services, LLCDelaware
Momentum SNCFrance
MS Federal Services, Inc.Nevada
MSFS Holdings US, Inc.Nevada



MT Holding Corp.Delaware
National Nuclear Corporation LimitedUnited Kingdom
National Security Technologies, LLCDelaware
Nuclear Laboratory Partners of Canada, Inc.Canada
OneAimUnincorporated joint venture
Pacific Architects and Engineers, LLCDelaware
Pacific Operations Maintenance CompanyCalifornia
PAE (Australia) Pty. LimitedAustralia
PAE Applied Technologies International LLCDelaware
PAE Applied Technologies LLCDelaware
PAE Canada, Inc.California
PAE Colombia Ltda.Colombia
PAE Design and Facility ManagementCalifornia
PAE FoundationBosnia and Herzegovina
PAE Global Support LLCDelaware
PAE Government Services Colombia S.A.S.Colombia
PAE Government Services Mexico, S. De R.L. De C.V.Mexico
PAE Government Services, Inc.California
PAE Humanitarian Response LLCDelaware
PAE India Support Center LLPIndia
PAE InternationalCalifornia
PAE Justice SupportVirginia
PAE LLCDelaware
PAE Logistics LLCCalifornia
PAE Services Canada Inc.Canada
PAE Shared Services LLCDelaware
PAE Shield Acquisition Company LLCDelaware
PAE Training Services, LLCDelaware
PAE Worldwide IncorporatedDelaware
PAE-Perini LLCDelaware
Phoenix Consulting Group, LLCAlabama



PUMMAUnincorporated joint venture
PWR Power Projects LimitedUnited Kingdom
Quality Systems Engineering Consortium, LLCCalifornia
RSI Amentum Environmental Solutions, LLCTennessee
SA Environmental Services II LLCNew York
SafeGUnincorporated joint venture
Savannah River Completion Alliance, LLCDelaware
Savannah River Missions Operations LLCDelaware
Savannah River Remediation LLCDelaware
Service Systems (Singapore) Pte. Ltd.Singapore
Services International LLCDelaware
Sotera Defense Solutions, Inc.Delaware
TATE, IncorporatedMaryland
The KeyW CorporationMaryland
The KeyW Holding CorporationMaryland
Triple20 LLCMaryland
UCOR LLC (fka URS-CH2M Oak Ridge, LLC)Tennessee
United Cleanup Oak Ridge LLCDelaware
URS Federal Project Services, LLCMaryland
URS Federal Services International, Inc.Delaware
USA Repository Services LLCDelaware
Washington Closure Hanford LLCDelaware
Washington Demilitarization Company, LLCDelaware
Washington Government Environmental Services Company LLCDelaware
Washington Savannah River Company LLCDelaware
West Valley Cleanup Alliance LLCDelaware
West Valley Nuclear Services Company LLCDelaware
WGI Global Inc.Nevada
Worldwide For General Services, Construction And Engineering Services And Subsistence Services LLCIraq
Worldwide Management and Consulting Services LLCDelaware



Worldwide Recruiting and Staffing Services LLCDelaware
WSMS-MK LLCTennessee