Which principle encourages military leaders to use the least force necessary to achieve objectives?

The principle that encourages military leaders to use the least force necessary to achieve objectives is proportionality. This principle is a fundamental tenet of the laws of armed conflict, aiming to ensure that the force employed in military operations is appropriate and commensurate to the military advantage sought.

By adhering to proportionality, military leaders are guided to evaluate the potential collateral damage and civilian harm that could result from their actions. This means they must carefully consider whether the expected loss or damage is justified by the anticipated military gain. The principle serves to limit unnecessary suffering and destruction, reinforcing ethical conduct and responsibility in military operations.

In essence, proportionality helps to strike a balance between military effectiveness and humanitarian considerations, making it essential for responsible military leadership.