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The brutal calculus of war: Is the killing of civilians ever justified?

A view of the rubble of buildings hit by an Israeli airstrike in Jabalia in the Gaza Strip on Oct. 11, days after the territory's militant rulers carried out an unprecedented attack on Israel killing hundreds of people and taking captives.
Hatem Moussa
A view of the rubble of buildings hit by an Israeli airstrike in Jabalia in the Gaza Strip on Oct. 11, days after the territory's militant rulers carried out an unprecedented attack on Israel killing hundreds of people and taking captives.

Updated November 11, 2023 at 7:53 AM ET

Israel is coming under mounting criticism for its actions in Gaza where more than 11,000 people have been killed, according to Palestinian officials, the vast majority of them civilians. This follows Hamas' attack on Israel last month that killed around 1,200 people.

Targeting civilians is a war crime. But what if there are civilians in or near a legitimate military target? This is where something in the laws of war called "proportionality" comes into play. As in, the military advantage must be proportionate to the loss of civilian life.

In such a case, the U.S. military uses what's called a "collateral damage estimate," or CDE, which determines how many civilians would be killed or wounded when a military target is hit, says Michel Paradis, a human rights lawyer who teaches at Columbia Law School.

And then you get into how valuable is the target. If it's a member of al-Qaida plotting the next attack, the calculus may include the possible collateral death of one or two civilians, but if the target, for instance, is Osama bin Laden, then a higher number of likely civilian deaths may be considered acceptable. The numbers are generated by military and civilian officials and are classified. And a decision to strike that target could go up the chain of command, depending on the number of casualties.

"This is an oversimplification," said Paradis, "but for example if the CDE is 1, then a lieutenant can order the strike. If it is 10, it must go to a major, is 100 it must go to a colonel, and if 1,000 it must go to a general. All along the way, you also have military lawyers consulting in the process in the hopes of keeping you honest."

Who decides?

"Who decides proportionality?" asks Aaron O'Connell, a retired Marine colonel who teaches at the University of Texas. He presented this scenario: "It is a reasonable person standard, and the standard is this: As long as the violence is intended for a legitimate military target, like a Hamas command center under the al-Shifa hospital, collateral damage is acceptable. Whether 20, 200 or 2,000 noncombatants get killed is the question the hypothetical person has to answer to make a judgment on whether war crimes occurred. A pretty loose standard."

Israeli officials have said they will take steps to limit civilian casualties, but it fell to a Pentagon official, Dana Stroul, to provide more detail during a hearing on Wednesday before the House Foreign Affairs Committee on the Israeli-Gaza war.

"They have dropped 1.5 million leaflets in Gaza asking civilians to evacuate," Stroul said. "They have sent over hundreds of thousands of text messages and made phone calls to cell phones. ... In our conversations with the Israel Defense Forces they have made clear they assess collateral damage estimates before they take strikes."

Israel is known to do a lot more in the way of precautionary measures, says Paradis, the human rights lawyer; this has not always been consistent.

"The most famous of these is 'roof knocking,' in which they drop a small but loud explosive onto the roof of a building that is going to be the target of a strike," he said. "They wait 15 minutes to an hour to let people evacuate, and then they conduct the strike."

But the attacks two weeks ago against a suspected Hamas leader inside a tunnel next to the Jabalia refugee camp in Gaza raised questions about proportionality and led to accusations of war crimes being committed by Israel. Some 50 civilians were killed in the attack.

"Given the high number of civilian casualties [and] the scale of destruction following Israeli air strikes on the Jabalia refugee camp we have serious concerns that these are disproportionate attacks that could amount to war crimes," the Office of the United Nations High Commissioner for Human Rights said in a statement.

Indeed, Secretary of State Anthony Blinken urged Israel to do more to protect civilians. Speaking to reporters in New Delhi, Blinken said, "Far too many Palestinians have been killed. Far too many have suffered these past weeks. And we want to do everything possible to prevent harm to them and to maximize the assistance that gets to them."

The issue of proportionality "is pretty subjective," said a retired senior military officer who served in the Middle East and requested anonymity given the sensitivity of the topic. "The attacker makes the determination, but ultimately public opinion will decide. Israel will probably do what it believes it must to win while trying to mitigate the domestic and international consequences by using as much precision as they deem appropriate."

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Tom Bowman is a NPR National Desk reporter covering the Pentagon.