A method for determining an engagement plan for an air defense system comprising at least munitions (Mi) capable of being fired from launchers, at least some of said launchers being capable of firing several munitions (Mj), the engagement plan consisting in allocating munitions (Mj) from the air defense system to aerial threats referred to as targets (Ci), each allocation being a group of elements representing parameters for adjusting the air defense system in order to deal with the aerial threats, said method comprising the following steps, carried out automatically and successively, by a device for determining an engagement plan: - a data reception step (E5A) implemented by a data reception unit of the device for determining an engagement plan and consisting in receiving data concerning at least the available munitions (Mj) and of the targets (Ci) detected; and - a processing step (E5B) implemented by a processing unit of the device for determining an engagement plan and consisting, with the aid of the data received in the reception step (E5A), in forming the engagement plan, said engagement plan being used by the air defense system to defend a particular zone against the aerial threats, - the data reception step (E5A) consisting in also receiving, for each launcher of munitions (Mj) of the air defense system, on the one hand the number of munitions (Mj) of the launcher representing a first constraint concerning the munition (Mj) of said launcher, and on the other hand a number of firing dates in the availability window representing a second constraint concerning the firing dates; and - the processing step (E5B) consisting in determining the engagement plan, taking into account said first and second constraints, characterized in that said processing step (E5B) includes at least: • a first sub-step (E5B1) consisting in determining, for each pair of target (Ci) and munition (Mj), a so-called conventional benefit which represents a parameter allowing quantification of the interest of using the munition (Mj) to neutralize the target (Ci), said conventional benefit depending on a probability that the munition (Mj) destroys the target (Ci); • a second sub-step (E5B2) consisting in determining, for each pair of target and munition, a so-called adapted benefit, taking into account potential conflicts between allocations; and • a third sub-step (E5B3) consisting in implementing an auction algorithm taking into account said first and second constraints and using said adapted benefits for all the pairs of munition and target, in order to determine the engagement plan, said engagement plan comprising, for each of said targets (Ci), the allocation, on the one hand, of at least one particular munition (Mj) from a particular launcher and, on the other hand, of a firing date of this munition (Mj), this allocation satisfying said first and second constraints. - a data reception step (E5A) implemented by a data reception unit of the device for determining an engagement plan and consisting in receiving data concerning at least the available munitions (Mj) and of the targets (Ci) detected; and - a processing step (E5B) implemented by a processing unit of the device for determining an engagement plan and consisting, with the aid of the data received in the reception step (E5A), in forming the engagement plan, said engagement plan being used by the air defense system to defend a particular zone against the aerial threats, - the data reception step (E5A) consisting in also receiving, for each launcher of munitions (Mj) of the air defense system, on the one hand the number of munitions (Mj) of the launcher representing a first constraint concerning the munition (Mj) of said launcher, and on the other hand a number of firing dates in the availability window representing a second constraint concerning the firing dates; and - the processing step (E5B) consisting in determining the engagement plan, taking into account said first and second constraints, • a first sub-step (E5B1) consisting in determining, for each pair of target (Ci) and munition (Mj), a so-called conventional benefit which represents a parameter allowing quantification of the interest of using the munition (Mj) to neutralize the target (Ci), said conventional benefit depending on a probability that the munition (Mj) destroys the target (Ci); • a second sub-step (E5B2) consisting in determining, for each pair of target and munition, a so-called adapted benefit, taking into account potential conflicts between allocations; and • a third sub-step (E5B3) consisting in implementing an auction algorithm taking into account said first and second constraints and using said adapted benefits for all the pairs of munition and target, in order to determine the engagement plan, said engagement plan comprising, for each of said targets (Ci), the allocation, on the one hand, of at least one particular munition (Mj) from a particular launcher and, on the other hand, of a firing date of this munition (Mj), this allocation satisfying said first and second constraints.