WASHINGTON (AP) — The Pentagon has revised its rules of war to put more emphasis on the need to reduce civilian casualties and avoid “excessive harm” to people and property when planning and conducting attacks.

The changes to the Law of War manual include a new section that lays out the need for commanders to weigh any potential military advantage gained by an attack against the potential for collateral civilian injuries or deaths. And it says the military should take “feasible precautions” when planning and conducting attacks.

Precautions laid out in the manual reflect what commanders have been doing on the battlefield, including in Iraq and Syria, amid increased scrutiny of civilian casualties in the fight. But the changes formalize the current policies, updating the document that was released in June 2015.

The updated manual was released Tuesday.

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Protecting civilians in armed conflict is critical, and it’s important that our legal guidance is clear and practical,” said Defense Department General Counsel Jennifer O’Connor. “This version of the manual provides greater clarity and also reflects important developments, such as the president’s recent executive order on civilian casualties.”

The new version provides more details on the need to identify areas where military targets are more likely to be located and civilians less likely to be present. And it lays out examples of when the military has made decisions to forego an attack because of potential civilian casualties.

And it makes clear that subordinates should not comply with orders that are “clearly illegal,” including instances when a commander might order an attack that could be expected to result in excessive civilian casualties.

According to senior defense officials, military leaders planning operations against the Islamic State group in Iraq and Syria may authorize strikes where up to 10 civilians may be killed, if it is deemed necessary in order to get a critical military target.

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That is a change from the earlier policy that called for an assessment that zero would be killed. Officials said the change was made because of concerns that the military wasn’t being aggressive enough in its targeting.

A senior official, however, said that U.S. commanders have used that expanded authority only once in the past year since the change was made. The officials were not authorized to discuss the matter publicly so spoke on condition of anonymity.