What constitutes a "danger close" call when requesting fire support?

A "danger close" call refers to a request for artillery or air support that is fired within a specific distance of friendly troops. The threshold for this call is established as 600 meters. This guideline exists because engaging in combat operations at such proximity poses a significant risk of collateral damage and can jeopardize the safety of friendly forces. When a fire request falls within this range, it necessitates additional caution and coordination to ensure that friendly personnel are adequately protected while still achieving the desired combat effectiveness against enemy forces.

The other options don't accurately capture the definition of "danger close." For instance, firing within 400 meters of enemy troops may be tactical but does not provide clarity about the proximity to friendly forces. Indicating a need for immediate air support does not inherently imply a "danger close" scenario, as this could refer to any distance based on the urgency of the situation. Calling for fire in an area where civilians are present raises serious concerns about civilian safety and legality but does not specifically pertain to the "danger close" parameters concerning the proximity to friendly units.