MCO 3100.4A — Marine Corps Cyberspace Operations

MCO 3100.4A governs Marine Corps cyberspace operations, including offensive, defensive, and DOWIN operations.

Search MCO 3100.4A

  • Publication number: MCO 3100.4A
  • Title: MARINE CORPS CYBERSPACE OPERATIONS
  • Date: 25 Mar 2026
  • Proponent: 03000 Operations & Readiness
  • Status: Current

View MCO 3100.4A on armypubs.army.mil


It establishes policy, guidance, organizational responsibilities, roles, authorities, and relationships for cyberspace operations. It covers DOWIN and DCO-IDM missions, cyberspace fires, training, coordination, resourcing, and command processes.

Applies to: (2) This Order is applicable to the Marine Corps Total Force.

Topics covered

  • Offensive cyberspace operations
  • Defensive cyberspace operations
  • DOWIN operations
  • DCO-IDM missions
  • Cyberspace fires
  • Marine Corps Cyberspace Environment
  • Cyber Mission Force certification

Questions and answers

What are DOWIN operations supposed to do?

The DOWIN operations mission is to secure, configure, operate, extend, maintain, and sustain DoW cyberspace to create and preserve the confidentiality, availability, and integrity of the DOWIN. (paragraph 6)

What are DCO-IDM missions?

DCO-IDM are the form of DCO mission where authorized cyberspace defensive actions occur within the defended network or portion of cyberspace. (paragraph 6)

Where are cyber fires planned and executed within a MEF?

Within a Marine Expeditionary Force (MEF), these fires are planned and executed from the Information Coordination Center (ICC) as part of the MEF Information Group (MIG) in support of the MEF Fire and Effects Coordination Center (FECC). (paragraph 2)

When can cyberspace fires be executed?

Execution of these cyberspace fires may only occur when authorized. (paragraph 4)

What is required before executing cyber operations?

Deconfliction of cyber operations is required before execution. (paragraph 5)

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