Story highlights Donald Trump's call to kill terrorists' families would be a war crime, expert says

Ex-consultant to Israeli PM Benjamin Netanyahu says it would be a moral and operational failure

(CNN) A leading Israeli counter-terrorism expert says Donald Trump's call to "take out" the families of terrorists would run afoul of international law and degrade the moral standing of the U.S.

"Any deliberate attacks aimed against civilians is a war crime, regardless if they are family members of terrorists or presidents or presidential candidates," said Boaz Ganor, a former consultant to Israeli Prime Minister Benjamin Netanyahu.

"Adopting this policy is immoral and against the common liberal democratic values," added Ganor, the founder and executive director of the International Institute for Counter-Terrorism in Israel. "Deliberate attacks against the terrorist families is blurring the moral differences between the terrorist organizations and the state which is fighting terrorism. This by itself might benefit the terrorists which are trying to claim that they are fighting a moral war against relentless and immoral entity."

On Wednesday, Trump responded to a question on Fox News about minimizing civilian casualties in the fight against ISIS by saying the U.S. should hit the kin of enemy fighters.

"You have to take out their families, when you get these terrorists, you have to take out their families," Trump said. "When they say they don't care about their lives, you have to take out their families."

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