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Never in recent memory has the relationship between law and war been so central to strategic legitimacy. This has resulted in both positive evolutions of the law of armed conflict (LOAC) and a remarkable increase in interest, understanding, and analysis of this law. No state, or even non-state group, is immune from the increasingly informed critique of its planning and execution of military operations and the quite proper demand that its military personnel comply with LOAC obligations. Central to the regulation of hostilities are the core LOAC principles of distinction and discrimination. Distinction mandates restricting deliberate attack to only those persons, places, and things that qualify as lawful military objectives pursuant to conventional and customary international law. Discrimination imposes an additional obligation to forego engaging in such an attack whenever the incidental and collateral effects will be indiscriminate, and thereby unjustifiably endanger the civilian population. While Article 51 of Additional Protocol I establishes a three-part definition of indiscriminate for purposes of implementing the discrimination obligation, an “excessive” impact on civilians and civilian property—the so called proportionality rule—is a definitive standard for compliance with the discrimination obligation and is central to debates on the legality of employing lethal combat power during contemporary armed conflicts. This Article will explain why the precautions obligation should be universally embraced as a core LOAC principle, analogous in significance to those of distinction and discrimination. To support this assertion, this Article will explain the relationship of precautions to both the targeting process and the implementation of those fundamental substantive LOAC principles. This Article will ultimately propose that the true scope of the precautions obligation in the targeting process imposes a more comprehensive obligation than the measure included in Article 57, which is linked to this Article’s ultimate argument: precautions provide the critical link between the planning and execution of combat operations and compliance with the LOAC’s most fundamental targeting regulatory norms, distinction and discrimination.