If the incident commander decides to allow the building of origin to burn until additional resources arrive, what mode is this considered?

When the incident commander allows a building to burn while waiting for additional resources, it indicates a defensive mode of operation. In firefighting terminology, a defensive mode is utilized when the focus shifts from aggressive fire suppression within the structure to protecting surrounding structures and ensuring the safety of personnel. This strategy typically emphasizes controlling the fire's spread rather than attempting to extinguish it immediately.

In defensive operations, resources may be positioned to create a fire perimeter or to protect exposures without engaging directly with the fire, which is what would happen in an offensive mode. This approach is often necessary when conditions are deemed too hazardous for an aggressive interior attack, allowing firefighting personnel to wait for more adequate resources to arrive before committing to a direct assault on the fire. Thus, the decision to let the building burn until additional help arrives falls squarely within the parameters of a defensive strategy.