Defense Sector M&A: When do you submit an HSR filing to the Department of War?

Going forward, certain aerospace, defense, and national security mergers and acquisitions will require a concurrent Hart-Scott-Rodino (“HSR”) filing to the US Department of War (“DOW”), in addition to the standard filing made to the US Department of Justice (“DOJ”) and the US Federal Trade Commission (“FTC”).

Key Takeaways

• Section 857 of the National Defense Authorization Act (“NDAA”) adds new requirements for mergers and acquisitions involving defense and military sector suppliers or those involved in the defense industrial base and that meet certain criteria.
• Parties that meet the new criteria published by the DOW and that made a regulatory filing under the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (“HSR Filing”) may need to also submit a concurrent copy of their HSR Filing to the DOW.
• Filing parties may be required to provide Commercial and Government Entity (“CAGE”) codes¹ or Unique Entity IDs (“UEIs”)² for entities impacted by this transaction.
• This requirement will exist regardless of the changes with the New HSR Rules. Read the latest on the changes with the New HSR Rules here.

What triggers a concurrent HSR filing to the DOW?

Section 857 of the NDAA is vague and does not precisely specify which deals or parties are required to make a concurrent HSR Filing to the DOW. It provides only that “parties to a proposed merger or acquisition that will require a review by the Department of [War]”³ shall concurrently provide their HSR Filing to the DOW during the waiting period under Section 7A of the Clayton Act. It does not define which mergers and acquisitions “will require a review by the Department of [War].”⁴

In February 2026, the DOW’s Industrial Base Policy outlined key criteria⁵ for M&A transactions that may require review by DOW, including, but not limited to, transactions in which: 

1. Either party currently, previously, or intends to contract with or subcontract for the DOW.
2. One of the “six critical technologies vital to US national security” is involved in the transaction⁶:
   • Applied Artificial Intelligence: For example, this could include acquisitions involving artificial intelligence software, systems, or programs that support DOW strategies or artificial intelligence that the DOW embeds in command-and-control systems to build intelligent workflows used across the DOW.
   • Biomanufacturing: For example, this could include acquisitions involving the use of biological systems, like cells and microorganisms, that have been engineered, or that are used outside their natural context, to produce critical materials at scale.
   • Contested Logistics Technologies: For example, this could include acquisitions involving logistical technologies such as advanced satellite and radar technology, drones, uncrewed surface vehicles (USVs), unmanned underwater vehicles (UUVs), and unmanned aerial vehicles (UAVs).
   • Quantum and Battlefield Information Dominance: For example, this could include acquisitions involving communication and navigations systems.
   • Scaled Hypersonics: For example, this could include acquisitions involving hypersonic missiles and weapons, and other advanced firepower.
   • Scaled Directed Energy: For example, this could include acquisitions involving high-energy lasers, microwave technologies, or other energy solutions used by DOW.
3. Aspects of the Department of Homeland Security’s Defense Industrial Base critical infrastructure sector are involved, which broadly includes the research and development of military weapons systems, subsystems, and components or parts.⁷
4. Either party has intellectual property in the above critical technologies or critical infrastructure.

What happens if you meet the DOW’s criteria?

If a party meets the criteria above, there are a few key steps that counsel for the party will need to take, including:

1. Email the DOW M&A Division to inform them of the contemplated transaction and state whether the party has submitted an HSR Filing to the FTC/DOJ.
2. DOW will send a link to upload the materials through a secure channel (e.g., the DoD Secure Access File Exchange System).
3. Prepare to provide relevant CAGE and UEI codes for the entities impacted. 

DOW affords all submitted HSR Filings the same confidentiality provisions afforded by the HSR legislation, meaning that the HSR Filings are highly confidential, subject to FOIA requirements, and are not provided to third parties. HSR Filings are not shared with other DOW divisions and the HSR Filings will be destroyed by DOW after the waiting period under the HSR Act has expired or DOJ/FTC have otherwise closed their investigation.

DOW Review of Mergers & Acquisitions is Not New

Historically, the then-Department of Defense (“DOD”) has been involved in the review of mergers impacting the defense industry, defense contractors, or the DOD’s interests.⁸ In 2017, DOD revised and re-issued a policy statement outlining how then-DOD staff should assess the effects of a proposed merger involving defense supplier.⁹ The 2017 directive stated that the competitive assessment for these transactions must consider: (1) national security, (2) competition for DOD contracts and subcontracts, (3) potential restriction of a critical supplier to competitors of the merging parties, (4) potential benefits for then DOD such as cost savings, (5) risks to the financial stability of critical military capabilities, (6) any other factor that might affect satisfactory completion of any current or future DOD program or operation, and (7) any impact on DOD access to affordable or innovative sources to include impediments to obtain essential data rights.¹⁰ Nothing in the NDAA voids this directive and parties should expect DOW to rely on the 2017 directive in future reviews.

Practical Implications

1. Analyze the competitive implications of deals in the defense and national security sector early to avoid delays. As M&A deals in the defense, aerospace, and national security industries increase, including in defense tech and mission software space, it is important to consider how DOW may view the competitive effects of a transaction alongside other antitrust and CFIUS considerations. Early engagement with experienced antitrust counsel can help you navigate these considerations. Compliance with the new NDAA requirements is mandatory.
2. Plan to make a concurrent filing if your deal is involved in the defense sector. The additional criteria published by the DOW’s Industrial Base Policy is broad. Parties can correspond with the DOW to request guidance as to whether a transaction is subject to a concurrent filing. Parties should not be surprised if the DOW reaches out to request a copy of an HSR filing if the parties do not make a concurrent filing.
3. DOW, DOJ, and the FTC will continue to collaborate during deals impacting the defense industry. For deals in the defense industry, there has historically been interagency collaboration between the DOJ, FTC, and the DOW. Parties should expect that this collaboration will continue and will likely increase.

_{1 CAGE Code, Def. Logistics Agency, Dep’t of Def., https://www.dla.mil/Working-With-DLA/Applications/Details/Article/2920893/cage-code-commercial-and-government-entity-code (last visited Feb. 9, 2026).
2 Unique Entity ID is Here, Gen. Servs. Admin (June 5, 2025), https://www.gsa.gov/about-us/organization/federal-acquisition-service/fas-initiatives/integrated-award-environment/iae-systems-information-kit/unique-entity-id-is-here.
3 National Defense Authorization Act for Fiscal Year 2024, Pub. L. No. 118-31, § 857, 137 Stat. 136 (2023). 
4 Id
5 Mergers & Acquisitions, Indus. Base Pol’y, Dep’t of Def , https://www.businessdefense.gov/ibr/gies/ma/index.html (last visited Feb. 9, 2026).
6 Id. The Office of the Under Secretary of War for Research and Engineering has identified these as six Critical Technology Areas (“CTAs”), which the DOW has stated it is developing to meet national security demands. The examples identified in this section have been adapted from the DOW’s descriptions of what constitutes a CTA. See, e.g., https://www.cto.mil/wp-content/uploads/2025/11/CTA-One-Pager-Option-Nov2025.pdf.
7 Defense Industrial Base Sector, Cybersecurity and Infrastructure Security Agency, Dep’t of Homeland Sec., https://www.cisa.gov/topics/critical-infrastructure-security-and-resilience/critical-infrastructure-sectors/defense-industrial-base-sector (last visited Feb. 9, 2026).
8 Joint Statement of the Department of Justice and the Federal Trade Commission On Preserving Competition in the Defense Industry, Dep’t of Just. & Fed. Trade Comm’n (Apr. 12, 2016), https://www.ftc.gov/system/files/documents/public_statements/944493/160412doj-ftc-defense-statement.pdf (emphasizing that antitrust agencies rely on the Department of Defense’s expertise in evaluating mergers impacting the defense industry). 
9 Dep’t of Def., DOD Directive 5000.62, Review of Mergers, Acquisitions, ,Joint Ventures, Investments, and Strategic Alliances of Major Defense Suppliers on National Security and Public Interest (Feb. 27, 2017), https://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodd/500062p.pdf.
10 Dep’t of Def., DOD Directive 5000.62, Review of Mergers, Acquisitions, ,Joint Ventures, Investments, and Strategic Alliances of Major Defense Suppliers on National Security and Public Interest (Feb. 27, 2017), https://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodd/500062p.pdf.} 

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