One of the very first things I was taught when I joined the C.I.A. was that we do not conduct assassinations. It was drilled into new recruits over and over again. Today, it seems that all that is left of this policy is a euphemism. We don't call them assassinations anymore. Now, they are targeted killings," most often performed by drone strike, and they have become America's go-to weapon in the war on terror. There have been many who have objected, claiming that the killings inspire more attacks on the United States, complicate our diplomacy and undermine our moral authority in the world. Yet the targeted killings drone on with no end in sight. Just counting the campaigns in Pakistan, Yemen and Somalia, the Bush administration conducted at least 47 targeted killings by drones, while under the Obama administration that number rose to 542. America's difficult relationship with targeted killing and the dilemmas we may face in the future are beautifully illuminated by the longer story of Israel's experiences with assassination in its own endless war against terrorism. Israel has always been just a bit farther down this slippery slope than the United States. Americans now have a terrific new introduction to that story with the publication of Ronen Bergman's "Rise and Kill First: The Secret History of Israel's Targeted Assassinations."