Establishment of the ICS modular organization is the responsibility of the:

The establishment of the Incident Command System (ICS) modular organization is fundamentally the responsibility of the Incident Commander. The Incident Commander is the individual designated to direct all operations at an incident site. This person is accountable for the overall management and strategy of the incident response and must ensure that the organization is structured effectively to meet the incident's needs.

As the leader, the Incident Commander assesses the situation, determines the type and amount of resources needed, and establishes the command structure that allows for a flexible and scalable response. The modular organization of ICS enables the response team to expand or contract according to the severity and complexity of the incident, allowing for a tailored approach to various emergency situations. The Incident Commander is positioned to implement this structure by ordering the creation of sections and branches, as necessary.

Other roles like the Planning Section Chief, Emergency Operations Center, and Logistics Section Chief have their own critical functions during an incident, but they operate within the framework and organization established by the Incident Commander. Understanding this distinction is key to grasping the dynamics of emergency management and command structure.